english
1
general::
Phrase(s): but good severely; thoroughly. • She told him off but good. • Joe beat up Bill but good.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Emphatically, thoroughly, as in Ruth decided to clean up the whole yard but good. The word but in this colloquialism functions as an intensive. Also see AND HOW.
American Heritage Idioms