I can understand your thoughts here about "come" when used:

"God, Filch, yes, right there, I'm gonna cum."

But, I've seen it used as a noun - and for some reason, my brain thinks of the byproduct of "come" as "cum". *clears throat*

Sirius wiped his eyes slowly, the thick streams of cum warming his eyebrows. That Dumbledore was one nasty motherfucker.

But, I know I grew up with come = verb and cum = noun. I wonder, is it a regional thing? Is it a class thing? Is it an entire world vs. kaalee thing?

Who knows?

Heh. Yes, I just cringed writing all of those sentences, because I am so pure and chaste.