I agree with AGDee...
The thing is, (okay two things) 1) maybe Caleb was so drunk that doesn't really remember either and 2) he was hanging all over some random too, so he's probably embarrassed. I also don't think he would assume you had sex with random boy, he most likely has no idea you seriously hooked it up so don't even worry about it. He probably feels like a jackass too. Next time you see him say something about that being a drunken night and he'll probably agree. If he's a jerk to you then he's too much of a judgmental ass for you to waste time worrying about it. As for random boy...don't bother with that. It wasn't your proudest moment and remember that this is all he knows about you...leave it be.
Threaded Mode