catcher’s mitt, n. — Green’s Dictionary of Slang

catcher’s mitt n.

[SE catch, i.e. semen + baseball imagery]

(US) a contraceptive diaphragm.

1999

D. Lypchuk ‘A dirty little story’ in eye mag. 8 July 🌐 She told him she had bought a brand-new catcher’s mitt and there was no need to play Vatican roulette. She went in the bathroom, put on her shower cap and came back.