Good question ! I wish I could explain it and give you a sensible answer but I can't. It just has to be something that males are attracted to. It attracts me also but I can't explain why! Good question as now I'll be trying to figure out the why!
This would be every guys ultimate dream to have two girls at once so they would very much love to come between them. But in all honesty, it doesn't turn on every gut, but most of the young boys just live for eating, sleeping and sex so they view this as a possible dream made in Heaven. Usually more often than not, nothing ever happens