Ha!

[Little_Girl]

what lil wayne always says in the middle of his songs

[Dave Paprocki]

some times used to show amusement.
sometimes used to show that what the person is saying, doing, trying to do,or asking is complete unresonable on your standards.

[Sonia]

Like lol, it is meant to convey a laugh in texting and instant messaging, but unlike lol, you must actually have laughed before typing it. It also implies more confident laughter.
Basically its a way to say lol, without having to say lol. Its great.