I'd just love this "D&D play - any edition char you want - TOGETHER" game.
"The wraith hits you! You are drained of 1d4 levels!"
"Haha! I play the 4e char! No level drain for me. Just losing a couple of healing surges!"
"Damnit!"
4e Cleric: "I use my healing surges to get myself back to full".
1e Fighter: "Great. Now heal me, will you?"
4e Cleric: *waves hand* "Here, spend a healing surge +1d6".
1e Fighter: "But i don't have... Aaaagh!"
"If the goblin enters this square, i get an AoO. I threaten it".
"The goblin gets +2 against OAs provoked by moving".
"Yeah, but does this help against AoOs? Just asking, of course!"
"Hey, i think as an 1e fighter, i get a passing attack regardless of any stuff!"
"Woah, your 1e fighter is sticky!"
*Looks down at his charsheet* "Damn this coolaid!"
"Okay, roll for system shock".
"Wah?"
"I mean, uh, make a... well... i attack your fortitude! Yes" *rolls* "Hit!"
"What happens nown?"
"You die"
"Oh. Well, my paragon path ability triggers. I'm back to life again"
"Wah?"
"You hear the voice of your god, scalding you. Suddenly you realize that you lost your powers!"
"But in 4e, you get your powers for good! Your god cannot take them away once you get them".
"Well, YOU decided to worship Cyric, did you? He isn't able to answer prayers in 4e, so it must be the 3e Cyric, so he can take away your powers. QED".
"I hate you so much".
"It will be very hard to open that knot. The bandit who made it had a Use Rope skill of +12!"
"Uh, i don't have Use Rope. I'm a 4e char".
"Well, my 1e thief doesn't have the necessary NWP".
"Ha! Use Rope is useful again! Wooohooo" *DM's victory dance"
Barbarian: "I hack the rope in twain. Regardless of edition".
Etc.