dead from the neck up

(adjective) very stupid

Example Sentences:

My new boyfriend is dead from the neck up, but he’s really handsome.

My co-workers don’t know how to do anything. They’re dead from the neck up. I can’t believe how dumb they are!

Similar idioms:

1. dead on one’s feet
2. over my dead body
3. pain in the neck
4. dead serious
5. dead set against something
6. play dumb