Personally, I would advise everyone to never, ever post "questionable" pictures of themselves online.

1. If you go on to have kids, their friends may find them and then bully your kids with them. "Dude, check it out. It's your mom!"
2. The Internet is never truly anonymous. There are always ways to find out who's behind the mouse mask beginning with IP tracking and going from there. It's really not that hard. And the photographers are always notorious for letting things out.
3. There are a ton of creeps that scour the Internet. Referencing (2) above said creeps may do something awful up to locating you and worse.

So yeah, for safety's sake, I would always suggest against it.