A slightly different take on Pink Floyd's 1987 album "A Momentary Lapse of Reason", used to describe the process in which the male anatomy overrides all rational decision making. Similarities can be drawn to "the heart wants what the heart wants", but "what the penis wants" is more powerful, visceral, and immediate.
Jim: Yeah, I had a momentary lapse of penis.
John: Why the hell did I out my crush like that and admit to having all these feelings...I don't even like her that much!
Jake: Blame it on a momentary lapse of penis!