not the brightest lightbulb in the chandelier

as defined by the reality TV show Forensic Mysteries on HLN, this a synonym phrase for "not the brightest person around"

boy 1) yo come to my backyard, i want to start a party by going out to weed

boy 2) are you an uptard, your dad, or mom will notice.

boy 1) nope my mom is not even home from work and my dad is not the brightest lightbulb in the chandelier, he will think we are trying to burn Cheetos on the barbecue or something.