I had to look it up on Urbandictionary and this is what I got:
The most annoying piece of shit in the world. It is commonly used by attention seeking whores. Some uses for it USED to be: Number sign Sharp sign (in music) Tic tac toe grid
But now thanks to twitter its a "HASHTAG". Used by annoying people.
Some people who use it:
99% of my school Whores Obnoxious hypocrites Anybody I hate


annoying
ridiculous
obnoxious