Did you have a brain tumor for breakfast?

A phrase made popular by the 1989 movie 'Heathers' and the 2014 musical of the same name. It is very similar in meaning to 'Are you retarded?'.

Heather Duke: Can I be red?

Heather Chandler: Did you have a brain tumor for breakfast? I'm always red

Heather McNamara: I've been looking forward to this all day!
Heather Duke: Did you have a brain tumor for breakfast?