Something that has happened that needs to be promptly covered up, so that no one gets pissed at all of you. It's a code word for what really happened...
For example, you and your best friend make out with her exboyfriend and his best friend while you were baked, and no one even enjoyed it anyway because you've been friends with
one of the guys since second grade, and the other one is like your brother, and you can't let anyone find out because it can't get back to the girlfriend of
one of the guys, who is also one of you and your friends good friends...
But when you all show up to arena later that day with red eyed and guilty looking, people area all like, "Where've you guys been?" and none of
you know what to say because you're all baked anyway, so you say that you got baked and did something really stupid, and then the person figures out what probably happened, and runs off and tells the guys girlfriends, and then she gets all pissed and thinks that you and your friend are whores, and are all pissed at the guys, and then everyone else finds out and gets all pissed off and moody and angst ridden, and then someone suddenly blurts, "
what the hell were you thinking?" and you, thinking
quickly on you're feed reply...
"Actually, the stupid thing we did was put rocks in a blender."
And everyone's all like, oh, that's dumb, and gets over it because they're in high school and they think that EVERYTHING matters and is a big deal.