What is :)~?
1.
A derivative version of the :P smiley, this one instead means the same as :P but in a lighthearted manner to alleviate some of the insulting vibe that is normally felt with the use of :P. It is used in the same context as the standard :P but to basically add an underlying context of "no offense (just being silly)" due to the fact that although this emoticon is sticking it's tongue out, it's also smiling friendly at the same time.
Secondary definition and use: Sometimes as a replacement for a :) smiley, but to suggest some sexual innuendo (from the smiling happy face to the inclusion of a tongue, bringing to mind cunnilingus)
Per first definition:
friend A: I did prty well in engish lcass
friend B: I can see that :)~
friend A: Arg, perfect timing on the typos...
friend B: np, lol
Per second:
n00b A: You usually just sit here all alone?
n00b B: Not always, sometimes I have a bit of company :)~
See