In the group's second or third session, we were investigating a chain of kidnappings (campaign: The Shackled City - please no spoilers) and were in a gnome locksmith's home/shop. Apparently, creatures have been coming from below his shop and entering into the city, and he was forced to give them the keys. Around this time, my ranger makes a brilliant spot check and notices that under a cauldron in the center of the room, two beady yellow eyes are watching us. I exclaim at the top of my lungs, "BEADY EYES UNDER THE CAULDRON!!" The DM chuckles and says, "Well, you didn't specifically say "out of character", so the eyes vanish. A moment later, dozens of creatures come bursting out of the secret doorway under the cauldron. Roll initiative." We were all laughing so hard that we couldn't roll. "Beady eyes under the cauldron" has been an inside joke ever since.
I have lots of other stories, I'll be back later.