silly
Definitions
Having or showing a lack of common sense or judgment; absurd and foolish.
Playfully mischievous or lighthearted in a way that is not serious.
Dazed, stunned, or incapacitated, often to the point of being senseless.
Examples
It was a silly mistake to leave the keys inside the locked car.
The children put on silly hats and danced around the living room.