An occasional occurrence for a male. This phenomenon occurs when a man tries to urinate with a fully erect penis. Confused at whether the male is either peeing or ejaculating, the penis thrusts out multiple, short, hard bursts of urine which gives the male a sensation that confuses him very much.
The act of "half cumming" in which a man can feel ejaculation coming on, and then, at the first twitch of his scrotum, can control and then stop the orgasm, thus creating stamina he didn't know he had!
Jack was in full control until his girlfriend started screaming for him to come which caused "pre-ejaculation", but, after much concentration about tennis, he was able to stop his scrotum from twitching, and instead of cumming, rode for another hour and 11 minutes!