It is an idiom in which

1. This person can and will hurt you, and they will do it with out you knowing.

Or

2. This person is dangerous and menacing, and does their action without warning or knowing.

This is the absolute difference of all bark no bite
Bro this guy went up behind me and almost body slammed me, luckily I was able to escape but that man did it with no warning.

Bro he really does all bite no bark.
by Brains/clever November 8, 2023
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