That'll do it! When you feel the cock head start to buck and twitch, banging against your prostate, your own cock will involuntarily release its load due to sheer ecstasy
I was top of a guy a few weeks ago, bouncing up and down on him, his cock was about 9inc.. He climaxed hard in me and I felt his cock pulsating and I blow my load at the same time, it was a vary intense felling and satisfying..