Re: Girls ends every single sentence with a ":p"
It usually means that she is joking or being playful with what she is saying. It isn't really too important by itself, but what it's attached to. Some people tend to put that after everything they say or could be a text signature. But is an indication of a positive, playful, or joking nature. Don't focus on it too much just look at it follows it's meant to emphasize the tone of the sentence.
*Dance With The Devil*
Remember That You're Not On My Level