Few fries short of a Happy Meal phrase informal derogatory
A "Happy Meal" is a children's meal sold at McDonald's fast-food restaurants that usually includes French fries.
Used to indicate someone is not intelligence or of questionable mental capacity
He's a few fries short of a Happy Meal, I'm afraid. Possibly, he can't help you anything.
Extremely stupid
Very stupid, or silly
Stupid or crazy
(n): a fool person,
(adj): stupid, foolish, silly
A stupid person or an idiot
Something or someone has been somewhere and become so familiar that it is hard for you to accept that place without them.
He was here for such a long time, so he was part of the furniture.