Late Drunk
A late drunk is someone who doesn't feel the full effects of alcohol sometimes up to as much as an hour after they've stopped drinking.
Fred: Hey John you didn't seem too bad the other night considering how much you drank.
John: Ah I was a bit of a late drunk that night, I was all over the place about an hour after I left.
John: Ah I was a bit of a late drunk that night, I was all over the place about an hour after I left.