First off, hello and welcome to our forum.
When I mention to someone that I am in a sorority, I generally get the response, "So what do you do, party and get drunk?" I almost always get that response! In a calm, surprised tone, I usually respond with, "You know, that is not all it is about. Being in a sorority is actually work!" I tell them that because it is work, especially if you hold a position. Also, it let's that person I am speaking with know that it is not all about "partying" but that we do contribute a lot to our chapters.
I hate when people stereo-type. It just shows their ignorance!