(idiomatic) sneak thief, literally "to steal like a dog"

steal in, sneak in

late at night, the middle of the night / midnight

nighttime, the night, the period of time during the night

the entire night, the period of time throughout the night

puppy, dog / a sentinel / a snoop or spy / useless, wasteful

Alternative spelling of 犬

he / distal demonstrative, something far off removed from both speaker and listener: that / boyfriend

distal demonstrative, something far off removed from both speaker and listener: that, yon / particularly, male personal third person pronoun: he / by extension from he: boyfriend

he; boyfriend