Erections caused non-sexually become rare too [on ageing] (there are exceptions: the party piece of the poet Rupert Brooke was to dive into the River Cam and emerge with his penis at the perpendicular - it impressed Virginia Woolf no end when they went skinny-dipping) ...

 

(Hickman, Tom (2012-11-01). God's Doodle (Kindle Location 2441). Square Peg. Kindle Edition.)