Idiom of the day :- Laugh up one’s sleeve

Usage, examples and definition of the Idiom :-

From the fact that people sometimes hid their laughs behind their hands, we have this idiom. It means to be secretly amused — and usually because a person is quietly laughing at someone for failing or for being wrong. ‘I could sense that Jerome waslaughing up his sleeve at me when I didn’t pass my history quiz,’ Ron said.