expression
don't lend money to a man who doesn't have morning erections
Archaic proverb based on the folk belief that a man without morning erections is in poor health and may die before repaying a debt. Not used in modern Japanese.
「朝マラの立たぬ男に金貸すな」ということわざは、江戸時代の庶民の間で言われていたらしい。
The proverb 'Don't lend money to a man who doesn't have morning erections' is said to have been used among commoners in the Edo period.
The exact origin is uncertain; it appears to be an Edo-period folk saying reflecting pre-modern beliefs about health and virility.