猫腻

貓膩
māonì
(coll.) something fishy; shenanigans

CEDICT

colloquial

Entry Composition

1 猫 māo
  1. (dialect) to hide oneself
  2. (loanword) (coll.) modem

classifier: 隻
2 腻 nì
  1. greasy
  2. soft
  3. unctuous
  4. intimate
  5. tired of