sneaking
sneak-ing
verb
Moving quietly and secretly to avoid being seen or heard by others.
"He was caught sneaking out of the house."
adjective
Done secretly and often dishonestly, or a slight, unacknowledged feeling or thought.
"She had a sneaking suspicion he was lying."
Thesaurus
Synonyms: pilfer, lift, swipe, abstract, purloin, filch, nobble, snarf, cabbage, pinch, sneak, hook