what is it with us men that want to either 1. be with two women at the same time or 2. see two women in action with each other. i mean if you ask the average women she will probably tell you this situation has been presented to her in the past.
as for myself i have seen this happen with two women in the past. there was something very mysterious and exciting about what was happening before my eyes. seeing two women making love to one another seem so taboo but also erotic. unlike probably what most men would do she took her time at a very slow but steady pace. searching and probing all areas of the other woman body. no words being spoken just the sounds of gentle moans could be heard. as i watch it became more and more intense for me "what a turn on" and thoughts of "wow that how i should be doing it" for what seem like hours they were having their "fun" with each other. it had started out as me just being an observer. but after what seem like a lifetime of viewing pleasure i just in from behind on one of them and entered her. she motion back with her hips and continue to give pleasure to the other woman. what a thrill when i exploded.
so for me it may be the taboo of it all that intrest me and also its the erotic part that thrills me.