small tiger
Literal meaning: a tiger that is small in size, or a young tiger.
A small tiger was born at the zoo.
light drinker; occasional drinker
Idiomatic expression for someone who drinks only a little or rarely. Contrasts with 大虎 (heavy drinker).
See also: 大虎
He's a light drinker, so one glass of beer is enough for him.
Compound of 小 (small) and 虎 (tiger). The idiomatic sense likely comes from comparing a person's drinking capacity to the size of a tiger.