In the UK we call this a comma. Used mostly to introduce a qoute, it is also used randomly by irritating teenagers and people who dropped out of school or have never read a book above the literary standard of Guns 'n' Ammo. It can be exchanged with a number of other phrases, including I was all.
1. To introduce a quote: So I was like, "duuuude" and he was all "baaaabe".
2. Randomly: Like, oh my God, that is, like, so wrong.