In high school and college days, I used to hide behind the guitar and play at parties and friend's gatherings. These days I leave the guitar home, unless asked, or it's a music party. I didn't want to use the music as a barrier to interacting with people. If we've played professionally at an event and socializing takes place after the show, I will encourage other people to play and sit back and listen (they have, after all, already heard me). But some of the best music I've participated in has happened at friend's houses gathering informally, and there's nothing to beat it.