We have quite a few MMF and MMFF in the last couple of years. I (male) am not the least bi, but it doesnt really bother me to see the other guy naked, especially since we both know we arent going to touch each other. For me, the excitement of seeing her with another guy outweighs the downside of being in the room with another naked guy. My advice for someone that wants to try it, but is scared to get undressed with another guy around is to find another couple and make it a 4some.