shrinkage

arvonlasku

kutistuma The act of shrinking, or the proportion by which something shrinks.
The loss of merchandise through theft, spoilage, and obsolescence.
puhekieltä The reduction in size of the male genitalia when cold, such as from immersion in cold water.
1994 Peter Mehlman & Carol Leifer, "The Hamptons," Seinfeld, Season 5, Episode 20 (aired May 12, 1994), Spoken by Jerry Seinfeld (Jerry Seinfeld)

Do women know about shrinkage?

This is why guys experience "shrinkage" after they've been swimming.

That'll get their blood flowing. ... getting the blood flowing coz just the mere thought of jumping into that icy water was starting to get the shrinkage going.

And of course, one of the most important questions of all, especially among male plungers, is, "What about shrinkage?!"