I remember reading a story about some guy who got a cheap vasectomy in central america and his nuts swole up and he went to a real doctor who squeezed his balls and pus shot out his dick. You could probably do something similar with cock and ball torture. Like maybe you're just putting enough pressure on the epididymis to forcibly squeeze the cum out. But short of that no, I'm pretty sure Ballgasm is just a Mastodon song.
Coregasms, on the other hand...