expression
serves you right!; that's what you get!
A mocking, slangy exclamation used when someone gets a deserved comeuppance. Abbreviation of 様を見ろ (ざまをみろ). Often written with a small ぁ for emphasis.
See also: 様を見ろ
ざまぁ！だから言ったのに。
Serves you right! I told you so.
彼が転んで、みんなで「ざまぁ」と笑った。
He tripped, and everyone laughed, saying 'Serves you right!'