The phrase "brightest bulb" is often used to refer to someone who is very intelligent or smart.
Sentences with «brightest bulb»
Lilly is described as the «care taker» of the two, watching over her sister Ally (who may not be brightest bulb in the bunch!) (lionelslegacy.org)
Philips» Hue smart lighting system is getting onboard with Apple HomeKit, with Hub 2.0 embracing third - party IoT protocols alongside a bevy of brighter bulbs. (slashgear.com)
When I moved into my home with limited light fixtures, I ran out and bought bright bulbs for every light fixture only to discover that my home doesn't look good lit up like billboard. (blowingawayoutwest.com)