I have this one friend who does the weirdest stuff, and by "weirdest stuff" I mean something dumb followed by a high enough roll to get away with it. We all actually got into a crazy number of hijinks, but I'll tell the story of something he did in our first campaign.
So, I believe the party consisted of a human fighter, a human cleric, a drow sorcerer (my sister IRL), and a human rogue (me). We were staying in a tavern on probation (we started the game in jail and got out on a deal that we'd do jobs for the captain) and noticed a number of shifty figures at the bar. The cleric was highly charismatic (we were pretty certain he was a saint) so he went up and started chatting with some of the group members. My also charismatic rogue flirted with another one. Our sorcerer listened from across the room with her acute elven hearing. The cleric and I were getting on their good sides and were about ready to worm information out of them.
Then the fighter walked up and asked, "Hey, are you involved with anything shifty, lately?"
Cue anime levels of shock from the rest of us.
The people gave him cold non-answers while the cleric and I convinced them we didn't know him. Fast forward to that night. We finished a job and wanted to get back to the tavern unnoticed. My rogue, who wasn't much of a team player, decided to leave on his own. (He did that a lot.) The rest of them followed suite and split up. Our fighter was ambushed (three guesses why), knocked out, and woke up later in a pit sealed off with bars. He escaped into the undercity and rolled Gather Information check to get out.
Our DM was floored. She didn't even know what a critical success on Gather Information should do in that instance and had to take a ten minute break to call a friend for advice. To this day, it's remembered as the time he broke the DM.
To finish up the story: he ended up finding a pair of drunk and strangely knowledgable gnomes who told him the way out, bypassing the entire solo dungeon our DM had made him. He came out of a secret passageway in the cellar of our tavern, to the surprise of the tavern owner. He proceeded to ask the owner if she knew there was a passage to the undercity through there. She said, "What? No way!" He rolled insight, to which the DM shouted, "SARCASM!"