偷偷摸摸

tōutōumōmō
(idiom) surreptitious; sneaky

CEDICT

surreptitious; furtive; sneaky

Wiktionary

瞞著人做事，不讓他人知道

維基詞典

Entry Composition

1 偷偷 tōutōu
  1. stealthily
  2. secretly
  3. covertly
  4. furtively
  5. on the sly
2 摸摸 mōmō
  1. (neologism, onomatopoeic) mwah (sound of kissing)
  2. mwah (sound of kissing)
  3. to feel; to touch

Related entries

偷摸 tōumō surreptitious; sneaky