dude, i'm the same way on xanax (or any benzo). if i take a low dosage like 1-2mgs and go to a party or hangout with people, i am the life of the party. people seem to gravitate towards me and i am confident and social.
i am an introverted guy aswell, i find it hard to make and keep friends, so anything that helps me get out of my head and have a good time socially i fucking love!!! anything that stops me from over-analyzing what i say and do, and gets me very talkative i gravitate towards. i love the feeling of being that social and people-loving guy i've always wanted to be.
i also project onto people that are out-going and fun-loving. i tend to hang around them because those are the qualities i want, and i hope they will rub off onto me hahaha. though the reality is that i am truely not that type of person, and i have a hard time socially because most of the time, i want to talk to people and have fun, but i don't want to put the effort, if that makes sense? but when i'm on those drugs that make me, me then i want to talk my mouth off and laugh and have fun with others
there is also the side of my drug use that includes the rush which typically comes from opiates for me. this involves using drugs simply for the sake of getting high.