1530s, "sell alcoholic liquor by retail," of unknown origin, possibly from a Scandinavian source (e.g. Norwegian dialectal tipla "to drink slowly or in small quantities"). Meaning "drink (alcoholic beverage) too much" is first attested 1550s. Related: Tippled; tippling.
A revealing, esp a warning; a particularly useful clue: the tip-off on what's ahead (1901+)