let's see... dust off my way-back machine and see if I can summon up some memories of really wacky stuff.
There was one time when about 6 or 8 of my friends and I were playing Shadowrun. I was GM, everything was going smoothly, everyone was working well together and getting things done... and then one player says "I go shopping," and tries to make the rest of the session all about just his character, in an exchange that was something along the lines of:
Him: "I go shopping."
Me: "Alright, cool. What are you looking for?"
Him: "A pawn shop."
Me, confusedly: "...you want to buy..."
Him, cutting me off: "No, I'm going shopping at a pawn shop."
Me: "What are you planning on buying?"
Him, forcing the issue: "Have I found a pawn shop, or not?"
Me: "Yeah, sure... you get to a pawn shop called Murdok's, it's open even though it is the middle of the night, and looks pretty secure and well-stocked. What are you looking to buy?"
Him: "I go inside."
And so on, including me outright saying "No, stop it, no role-playing right now. What are you trying to have your character buy? This is Shadowrun, not Shopping-all-by-myself-like-a-goon-while-everyone-else-waits-run," and him getting bent out of shape that I was glossing over the boring details, which was ironic because...
Same guy, different game, and before the show-stopping shopping trip: The players were entirely in control of where they went and what they did when they got there, and could go on literally any kind of adventure they chose and I would put it together on the spot for them. The decision came down that this dude wanted his character to get a castle, so I presented some ideas of castles that maybe he could claim as his own. He chose the one seated in an island nation nearby with locals sending requests far and wide for someone to help them out because their good king had turned foul and monsters were plaguing their lands and lairing in the castle - so the adventure was all about exploring this castle, room by room, sorting out what the cause of the rumors was because the castle initially seemed entirely deserted when the party arrived.
And this player said, about 5 or so doors in "Ugh... I hate doors, it's so boring to do the step-by-step of see it, check for traps, listen, unlock, open and all that." to which I responded "No problem, man, if that stuff bores you we'll just skip from you picking what door to head through to me covering what happens next, assuming that you did all the little step-by-step standard procedures each time."
Of course, then he apparently got bored of waiting for me to tell him what his character sees after opening a door and decided to start interrupting me with "I kill it." every time I said some iteration of "You see..."
Which I answered with a, and I admit it was entirely petty of me to do so, demand of an attack and damage roll, which he obliged gladly until I got to the describing of the results of his attack: He opened a door, saw a desk covered in papers that might have provided some hint as to what was going on around the castle, and immediately destroyed them and it with one mighty blow of his (ridiculously powerful) keen icy, shocking, and flaming burst scythe +1.
Then there was a time I asked him for one of his just-opened pack of cigarettes because I had run out and wouldn't be getting more until the next day when I got paid, and he said "No, I've got to make this pack last me through the weekend," and another friend of ours that was present fished a quarter out of his pocket and said "Here, I'll buy one from you for a quarter," which was a deal he accepted and I got the cigarette I had asked for. The following day, I was met with proof that the one cigarette I'd asked for previously wasn't going to make the difference between that pack lasting him through the weekend either way. He showed up for a game session, and as he is walking in there are a few of us already sitting around getting ready, including that a friend and I were cracking open fresh cartons of cigarettes.
He asked our buddy "Hey, can I bum a smoke? I'm out." Our buddy responded "Oh, these aren't mine, Aaron bought them" which was true, but not really relevant since I had bought them for said buddy so there were his to do with as he pleased. So this guy looks to me and says, "Can I bum one?" and I say, "You got a quarter?"
He turned right around and left, didn't come back till the next week. I felt a little bad for it because I was just giving him a hard time for being so stingy (the group of us having had an established pattern of share and share-alike, including taking turns for one of us to take the other 6 out and treat them to a nice dinner, and that on more than one occasion each of the rest of us had given him our second to last cigarette, and then split the last one with him too), but he left so fast that I didn't get past holding back a laugh at his reaction to saying "I'm just <expletive deleted> with you, have a whole pack, dude," like I had planned on when the joke popped into my mind.
And, just so that I tell a tale that doesn't involve this one guy: Three of us (but I was the only one of three present for any of the above, if that matters at all) were hanging around waiting for other folks so we could go and do something I don't fully recall, probably was a parade day (Mardi Gras, New Orleans, all that [literal] jazz), and we decide to play some Shadowrun.
Got characters together pretty fast. I was playing an ork street samurai that typically paid the bills with P.I. work, and my buddy was playing that ork's big-dumb-troll stereotype friend. Our friend that was running this impromptu game (which was his idea, for the record) sets it up that we are a bit strapped for cash and don't really have anything on our plates yet, so we need to get out and do some legwork to find a paying gig. We do that, encountering some fun NPCs along the way (my favorite being the ganger that tried to mug us as we were heading to my car, but found himself out-bladed and out-chromed... only to later try to mug us downtown and be like "Uh... no... that was some other guy" because the GM had unintentionally described these two separate gangers the same way) and head back to the troll's apartment to plan how we are going to get the job we found done.
Then there is a knock at the door of the apartment, which my character answers because we did order some food and it could be the delivery guy. Nope, it's guys we've never seen before with shotguns and angry faces. So they both blast my character in the chest with the shotguns, which lays him out but managed not to actually kill him thanks to dermal plating, and proceed into the apartment... where they must have forgotten they had shotguns because the next hour of my life was sitting out of a 2-player game while the DM rolls out a fist fight between these 2 unnamed goons and a troll. They weren't even there to try and kill anybody, literally just to get our character's attention and deliver the message that some NPC I don't remember didn't want us doing whatever job we'd just been hired to do.
And they through my character out the window into a dumpster before they left (again, with their shotguns that must have only had the one shell each despite being described as pump-action, or maybe had some strange racist biometric safe-target system that won't let the trigger engage unless the barrel is pointed at an ork) because they didn't think I'd quite gotten the message yet.