[Captain_Obvious]

In a word: make a perv's day. Or several pervs' days, maybe.

There seems to be a pretty big gender imbalance going on on Omegle, and there are a lot of pervy guys, which is why this is a lot more fun for female dare takers. The dare itself is easy enough to adapt for the guys, I suppose, but it wouldn't be as fun.
You can also do it on Chatroulette or wherever, though I'm not sure if the populace there is as suitable. It probably is. I dunno.

So here's the dare:
Go to omegle.com. Go to the video part. (You'll need a webcam.)
Your face should be visible in your video feed. It should be easy to see you're a girl.
And then, well, just go about your business, mostly. Talk to people, have a nice chat, whatever. BUT.
A. Whenever you run into someone who's wanking on camera, you're not allowed to disconnect. Stick around and enjoy the show. If they're attractive, smile and give them compliments. You have to wait until they either disconnect or finish, before you can move on.
B. Whenever you run into someone who asks you to show them your boobs, you show them your boobs. If you run into someone who wants to see more, undress for them altogether. (Put your clothes back on before you move on to the next person, there might be people who don't want to see that.)

If you want a set time, you have to stay on there and follow these rules for at least one hour in all.

Easy mode: Ignore the people who ask for your boobs, just watch the wankers.
Hard mode: Whenever someone asks for your boobs, ask if it's okay if you take off everything.
Nightmare mode: Log on wearing just a bra and panties.