1 definition by Stonerhighbye
A person that can have many drinks, become drunk, and still function perfectly normal. It's hard to tell whether or not this person is drunk unless you ask them to recite something.
Girl: I was so drunk last night but I had a normal texting conversation with my boyfriend.
Other girl: That's weird but you might be a functional drunk.
Other girl: That's weird but you might be a functional drunk.
by Stonerhighbye November 29, 2013