laugh up your sleeve
US /læf ʌp jʊər sliːv/
UK /læf ʌp jʊər sliːv/
1.
暗自发笑, 偷着乐
to be secretly amused about something, often at someone else's expense
:
•
She tried to keep a straight face, but I could tell she was laughing up her sleeve.
她努力保持严肃，但我能看出她正在暗自发笑。
•
The politician pretended to be concerned, but everyone knew he was laughing up his sleeve at the public's gullibility.
这位政客假装关心，但所有人都知道他正在暗自嘲笑公众的轻信。