(someone) Vrb phrs. To bore someone greatly. E.g."That 8 hour seminar on nuclear physics bored the pants off me." The suffixal ..the pants off is often used as an negative intensifier, e.g."He just mithered the pants off me all morning." Similar idiomatic intensifiers are '..the tits off' and '..the arse off'.
BORE THE PANTS OFF
Meaning of BORE THE PANTS OFF in English
Slang English vocab. Английский сленговый словарь. 2012