someone who is holier-than-thou behaves as if they have better morals than other people I can't stand that holier-than-thou attitude that some vegetarians have.
holier-than-thou
mod. superior in piety; condescending. She has such a holier-than-thou attitude.
Take it down a thou(sand)!
in. Cool down!; Calm down!; Quiet down! You are wild! Take it down a thou and let’s try again to talk this out.