goofus

noun

a silly, foolish, or clumsy person

Usage: informal; often used affectionately or humorously

Examples

Stop being such a goofus and pay attention in class.
My brother is a total goofus when he tries to dance.
That goofus tripped over his own feet again.
Don't be a goofus—use the instructions before assembling it.
He's a lovable goofus who always makes us laugh.