An "outsider's" = non-native speaker's opinion: "like" is mostly used in American English and is a parasite word. As such it catches easily, especially when one is exposed to the environment where others use the word a lot. As explained already, it's a filler like "er", "um", "well", etc.
Like I don't know!
Word such as: like and um are called fillers. People use fillers in their sentence structure because they either haven't thought about what to say next or out of habit (which relates to the first answer). There are probably other reasons, but I don't know anymore.
I like it too lol
Because it's like so awesome to be like soooo radical
Hello like how's it going like?
No... I have other habits
Oh I'm just sure your not :)
And decreasing rapidly!
I've lately been putting "though" in lots of my sentences. It is annoying.
Lot's of people do it to fill pauses between there thoughts or don't know other words to use to describe what they are trying to say.