of all the cheek, nerve, stupid things to do, etc.!
of ˌall the ˈcheek, ˈnerve, stupid things to ˈdo, etc.!(informal) used to express annoyance, impatience, etc. at what another person has done or said: Of all the idiots, leaving his car unlocked in the middle of town!
This expression is often used without a noun, especially to show that somebody is annoyed: She said I was fat? Well, of all the ...!