What's with hash tags on tweets and facebook statuses?

[Alex]

I keep seeing these tweets and statuses about random stuff that goes on in that person's life..and then I'll see a "hashtag" that has something to do with what they're talking about, but it will be clever. Where do these hashtags come from and how would someone know which one to use?? An example is as follows: ‎6 more days folks! #getyourmoshfaceon

[d0ndela]

On Twitter they actually have a purpose of generating buzz on keyboards and make them trend, but on Facebook it's just a trend (no pun intended) that people have started putting them in their statuses.
It's totally up to you what you want to put in your hashtag, but it's an "easy way of sounding funny" and so many people are using it at the moment.
Blame Twitter