What does the Yiddish word goniff mean?

The Yiddish word "goniff" (pronounced "goh-nif") means thief or crook. It's a very strong word, implying someone who is dishonest and untrustworthy.

The word comes from the Hebrew word "ganav" (גנב), which also means "thief".

"Goniff" is often used in a humorous or ironic way, but it still carries the connotation of someone who is not to be trusted.