laugh up your sleeve

Meaning

1. laugh up your sleeve (at sb / sth)

   to be secretly amused about sth

From the same entry

• don't make me laugh
• he who laughs last laughs longest
• laugh all the way to the bank
• laugh in face
• laugh like a drain
• laugh on the other side of your face
• laugh out of court
• laugh till you cry
• laugh your head off
• not know whether to laugh or cry
• you have got to laugh
• kill yourself laughing