I lost my virginity in my last year of college in a MMF threesome. Scott, my best friend at the time, and his girlfriend Lisa sort of seduced me. We had all been out drinking on a Friday night and went back to their place off-campus and one thing led to another. We ended up spending the entire weekend doing just about every combination you can do with a MMF threesome. Scott was quite hung (much bigger than me). Lisa refused to let him do anal with her because of his cock size so I got that pleasure. We ended up doing a DP with Scott in her pussy. Feeling his cock rub my cock, basically through her, made me come almost immediately. We tried it again later that weekend and I lasted a little bit longer but not by much. It's just an amazing feeling. I think the "taboo-ness" of it also adds to the excitement.