"What the H!" A line by our very own Grunkle Stan in the episode "The Love God" in the hit show "Gravity Falls". It is used when the famous "Nightmare Head" scene is shown where Grunkle Stan makes a hot-air balloon modeled after his head and on top of it saying "I HEART KIDS." No hes not a pedophile you dumbass.
Stan: "Let 'er rip!"
Meaning to let the balloon go.
Soos lets go of the ballon.
Soos: "Oh no! A let-er ripped!
The letter R falls down on Soos
Stan: "What the H!"
Proceeds to be crushed by a balloon letter H.
Causing the sign to say "I EAT KIDS." And conveniently the balloon caught fire making it known as "The Nightmare Head"