LOL, for me "why" depends on "when"! Or maybe I should put that in past tense since prostate meds have me mostly cumming into my bladder. BUT--in the past. Right before I'd cum, it'd just be hotter than all fuck! The thought of it pushed me over the edge. Right after--that's when the numb nutz blues takes over, and it takes some willpower to follow through. Happily, I still get a small dribble from time to time, and usually lap it up. I know from experience that the follow through has a pay off in smug satisfaction, and leads to hardon #2 in short order!