SECRETS DON'T MAKE FRIENDS.
Umm well I've had certain things that I kept secret from certain people because I didn't feel like puttin' up with their reaction but I think I DO know what you mean.
Like if somehow you were a seatfiller for the VMAs, and you told everyone about it cause you couldn't keep it to yourself, then something happened and it turned out you couldn't go...then everyone would think you were lying about it in the first place.
Is that the kinda thing you're talking about? In that case, I would tell someone you trust but make sure you mention that it's not a sure thing, as Becky said.