sneak

verb

To move quietly and secretly, often to avoid being noticed or heard.

"He tried to sneak out of the pub unnoticed."

noun

A person who tells tales or acts in a deceitful, cowardly manner.

"Don't be such a sneak and tell tales on your mates."

Thesaurus

Synonyms: pilfer, lift, swipe, abstract, purloin, filch, nobble, snarf, cabbage, pinch, hook, prowler