swear jar

[ swair jahr ]
/ ˈswɛər ˌdʒɑr /

noun

a container into which a fine is paid when someone who has agreed to limit the use of profanity uses language that is vulgar, profane, or obscene: The swear jar didn't stop my uncle from cussing, but Mom let me use the money to buy a video game—so it worked out for me!

Origin of swear jar

First recorded in 1965–70