Take the 1000 stroke challenge.
We did this, and it was fantastic.
The rules are this… he must not cum until he completes the challenge, but he can take a break at any time, so long as he gets his daily strokes in without coming. If he fails to get his day’s required strokes in by midnight he must start over on the next day.
On the first day, he must endure 100 strokes without coming, and each day increase the number of strokes by 100, until the 10th day when he must endure 1000 strokes without coming.
When we did this, on his 6th day he had to work late, and by then could only take about 15 strokes at a time before needing a break to keep from coming. He was insanely horny, and the fact that midnight was just around the corner made the pressure that much harder to control. Midnight came before he finished 600 strokes, and he had to start over at 100 the next day.
We realized that by this point he was soooo insanely horny and sensitive, we had to budget out his strokes throughout the whole day to get them all in without him coming.
When he finally made it to the 1000th stroke (on the 16th day lol), he was already starting to cum, so I stopped stroking to let him enjoy his hard earned orgasm without me distratcting him with more stimulation ;)