Verb
(archaic, colloquial) To discover someone is much stronger, much more dangerous, and/or much more violent than they appeared at first, especially after laying hands on them or (cant, obsolete) in a failed attempt to rob someone who turns out to be a stronger robber.
(archaic, colloquial, figuratively) To discover someone who cannot be controlled or disposed of more generally.
Source: en.wiktionary.org