A Porn Nam is to porn as Nam is to veterans of the war of the same name. It's a horrific event that ruins not only your boner at the time, but quite possibly your porn viewing indefinetly.
Josh had a porn nam when he saw his Dad's porn folder full of trannies.

My porn Nam was seeing a MMF threesome where the guys were as interested in each other as they were the chick.
by Penguin Incarnate June 29, 2005
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