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The act of two males masturbating with one another and ejaculating at the same exact time. The result is the ejaculated sperm colliding with one another.
This should not be confused with a "San Franciscan Kiss", which is similar, but one male ejaculates into the urethra of another man during or before the other male's orgasm.
"Man, did you see Jack & Terry's room?"
"Yeah. It looked like a pulled a San Franciscan Pileup on the place!"
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