1. In other words, you want to encourage a playstyle that involves constant debate and bickering about every detail.
Me: "I attack the orc."
You: "When you go to kick him, he chops off your foot!"
Me: "I am carrying a sword, and..."
You: "Gotcha! You didn't specify how you attacked! You're footless!"
2. This is the only phrase that matters, really. From the OP: "The player had completely forgotten that the gauntlets of ogre strength and the ring were placed with the armor as part of the set (or he just wasn't paying attention when the barbarian told me he'd put it all together for later).". In other words, you want the players to always be paranoid about forgetting any detail. Combined with the above, this doesn't go anywhere good.
3. If the guy always on the phone is disrupting things or bothering you, that is a different issue - which is not justified by the behavior of "Gotcha!". From the OP: "Let me just say that my group is composed of my best friends,". Some friend you are! With a friend like you, who needs enemies? Always looking for ways to "har har" and "gotcha" at the expense of others. I get the impression that you are the guy just waiting for someone to fall asleep first during a sleepover so that you can shave eyebrows or give someone a tattoo on their forehead. You don't punish your friends. You don't "teach them lessons". You give them slack. And if someone is disrupting things, you make adult decisions about whether or not that player's behavior is a problem and if so, how you deal with that problem. Maybe the player doesn't actually want to play, but wants to "hang around" his friends who are together. If so, you can let that player run some monsters for example, or do something that caters to the player's wants/needs/desires.
I cannot believe that anyone actually thinks it is fun for the DM to be a jerk. And now all the players will be trained on the meta level to expect DM's to be jerks, that D&D to be a game about "gotcha!". I would also be very weary of someone who believes that if someone is inattentive that you are justified to "punish" and "teach a lesson" to that person.