I like it when it kind of catches me off-guard. Not anything too intense, but when you fall into a rythym stroking from behind her, or when she's rocking back and forth doing the reverse cowgirl, and I'm mentally slipping away into my own little world of pleasure, then all of a sudden there's five fingers more stimulation going on that I didn't see comming, OH BABY!! I'm usually only good for a few more seconds after that and then I'm over the edge. Sometimes I think she times it to make that happen, or waits until I seem to be drifting off into a "pleasure transe" or something like that before she cups the boys, but either way, it sure does feel good.