Top Definition
When two gay or straight male friends face each other standing up. They then masturbate to see if they can cum at the same time with their respective penises pointed directly across from each other. The two male friends then ejaculate simultaneously into each other's streams as they orgasm. The cum streams intertwine and proceed to enter the other partner's urethra, in which it nestles, having symbolized their joining of sperm forever. This whole act is a cumclasm.

If one of these partners came first, then he had the dominant specimen, and any time the partner who lost engages in the same competition with someone else, they immediately become 10 times more cum first because of the presence of the dominant sperm in their urethra.
"Dude, my girlfriend hasn't jacked me off in weeks, I don't know what to do,"

"Bro, I can help you with that. I bet you can't cum first if we had a cumclasm!"

"Dude, I so can!"

"Let's go bro! Cumclasm time!"
by BlabTRGH April 08, 2012

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