In the many I have had, only one chick made mention of the other guys smaller (then mine) cock size. In that situation, the guy did not care. I did have one other time, a girl in a 3 way (with her hubby) said my dick was much bigger than his. Kinda crewel that she said it in front of him several times. I'm sure it made him 'under perform' during our encounter. That said, sometimes, I was the smaller one. I was the least bothered, as I enjoyed the fun we had.