to laugh at someone secretly, often in an unkind way.
He persuaded people to believe in him and all the time he was laughing up his sleeve at them.
(often + at)
(redirected from be laughing up sleeve)
be laughing up (one's) sleeve
To be trying to hide that one is laughing at someone else. It seems like the popular kids are laughing up their sleeves every time I walk by. It's so infuriating.
be laughing up your sleeve
OLD-FASHIONED
If someone is laughing up their sleeve, they are secretly amused by something, often something silly that someone else has done. They must be laughing up their sleeves at our stupidity. Note: The image here is of someone trying to hide the fact that they are laughing by putting their hand or arm in front of their mouth.