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An acronym for 'shake my penis head' or 'shaking my penis head.' Derived from smh, or shaking my head, it's used in substitution for smh, usually in terms of sex, or just general conversation.
guy1: I was about to stick it in when I sobered up and realized the girl was fat, which made me lose my erection.

guy2: Smph, that's messed up.
by brodeo14 January 18, 2011