Ahhh, I had a good one recently.
So, the game just began, and the group had been attacked by swarms of little flying beasties (I homebrew most of my monsters). Anyhow, the mystic theurge/necromancer goes invisible and slips into a room. It’s a dead-end, and because of his atrocious move silently skill and the beasties’ high listen, they follow him. He gets lucky on the last roll, and manages to remain unseen… in a corner of the room, surrounded by hundreds of foot long flying leech things.
Me: “What do you do now?”
Him: “I dunno, what can I do? I’m screwed.”
Me: “Listen, you have to do something.”
Him: (sarcastically) “I crap my pants”
Me: “Alright, you crap your pants.”
Him: Wait, uhhh….
Me: Yeah, you crap your pants. it slips under your robe and falls to the floor. the beasties all look over, and descend upon you (rolls) ripping you to pieces.”