It's interchangeable. And since the spelling of "cum" qualifies as slang in this context, one would be more compelled by vocabulary propriety to not enlist the use of the vulgar spelling for a homophone that was meant to serve as a pun.
Man, I totally got it the first time through! I don't know what everyone else is smoking, but that was a genuinely good setup. Fucking amateurs, right?
And yeah, that will be my annual "I agree with Pariah" post. Seeya in '09, Parys!
