한술 더 떠요 · 한술 더 떴어요 · 한술 더 떠서 (ㅡ drops)
to go one step further (usually worse); to go even further
Example
형이 늦게 왔는데 동생은 한술 더 떠서 아예 안 왔어요.
My older brother came late, and my younger brother went one worse: he didn't show up at all.
Word parts
Literally 'to scoop one more spoonful'; 술 here means a spoonful.
Good to know
Usually negative: someone outdoes another in bad behavior.