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
If you fall for someone's trick the first time then they are at fault.
Are you going to mess with me again? Fool me once, shame on you; fool me twice, shame on me.