This guy doesn’t know when to say when — or when to keep his mouth shut.

Juan Carreras, 58, who cops say is an off-duty MTA bus driver, put his foot in his mouth when he was pulled over on East Tremont Avenue at around 4 a.m. yesterday, according to police.

Asked if he had been drinking, Carreras allegedly said, “Yeah, but not enough! I had one or two drinks.”

He allegedly blew a .19 on a Breathalyzer test.