A friend group is a collection of people from one part of your life, who don't necessarily know people from your other friend groups.
1. "This is going to be fucked tonight, like 3 of my friend groups are all blending at this party."
2. "I can't believe my co-workers, my BFF from grade school, and my grrls are all going to be here tonight. How random! I hate it when my friend groups collide - aarrggh!