No, it doesn't. Anyone who told you so was fibbing. Perl's design allows you to add your own keywords to the language in such a way that the parser knows their arity and any contextual coercions--in other words, as if they were operators defined in the parser itself. This is rare (it doesn't happen often) and it's almost never ambiguous, but because the language used to define these custom keywords is Turing complete, it's possible to create pathological cases which depend on random factors to define a keyword in one of multiple ways...

... but no one ever does that except to prove that it's possible.