Somebody is working with their head under an object or in a confined space, and they forget where they are. Perhaps they're concentrating on the task at hand, or they're distracted by something else. Then something (often a ringing phone or another person) catches their attention, and they straighten up abruptly, hitting their head. It's a bit like a pratfall on the other end of the body, or a static version of the Low Clearance gag.
Generally, this is Played for Laughs, so the person has a Hard Head and suffers no serious physical injury, though they are quite likely to be sore, flustered or embarrassed. As a result, the person may scold the person who interrupted them, or yell at the ringing phone before answering it. This may also be one way to illustrate that the character is a klutz. On the other hand, the gag may be a way to draw attention to whatever was done or said to cause the person to react this way, or to punctuate the person's surprise.
Common sites for this gag are under furniture or inside a cabinet (say, under the sink in a kitchen or bathroom) and under the open hood/bonnet/trunk lid of a vehicle. May prompt a verbal reaction referring to their new headache. Subtrope to Slapstick and Reaction Shot.
- In Akagami no Shirayukihime the titular heroine hits her head on the underside of a desk after she bends down to pick up a fallen letter and starts to stand up too quickly as she ducks back out from under it when she notices the previously overlooked note on the back.
- In Lucky Luke, this can easily happen to Rantanplan, the stupidest dog in the West. Once, he is taking a nap under a horse watering crate (where Jolly Jumper is drinking), when he hears Luke asks the saloon tenant to feed his horse and give a bone to his dog... and Rantanplan immediately straightens up at the prospect of food and hits his head. Twice.
- Peter Pan: Mr. Darling is introduced searching through his drawers for his missing cufflinks and hitting his head on an open drawer above him.
- This happens twice in The Cannonball Run, both with the characters working on an engine and hitting their heads on the hood. First, it happens to J.J. when Victor mentions..."Him". Later, it happens to Victor when Blake taps him on the back.
- This was a hazard both in and out of universe when filming The Lord of the Rings:
- During the scene in The Fellowship of the Ring where Gandalf visits Bilbo in his hobbit hole, Gandalf, stooping, accidentally backs into a chandelier (as part of the script). His actor Ian McKellen then promptly turns and accidentally smacks his head on the roof, an (unscripted) accident so funny that they left it in.
- In the gag reel for Fellowship, this happens also to the crew. Everyone's sitting inside the hobbit hole listening to directions, then when the meeting ends they all stand up and hit their heads on the roof. Then everyone falls to the floor.
- In Mary Poppins, George Banks is looking in the fireplace for the childrens' notice for a nanny that he threw there (which Mary has just produced). His wife enters and calls his name, causing him to bang his head on the fireplace. In a scene immediately prior, he had already bumped his head for much the same reason when Mary asked if he'd lost something.
- WarGames: When David Lightman visits his programmer friend Jim, Jim has his head under a table. When David says his name, Jim raises his head and bumps it on the table.
- Who Framed Roger Rabbit:
- In Cheaper by the Dozen, Dad has recently pulled a practical joke on his children, telling them to look in the engine for a bird and then honking the horn loudly. One day when Dad is having to fix the car after a family picnic, one of the younger children sneaks into the car and presses the horn, causing him to hit his head on the hood and burn his wrist on the exhaust pipe.
- Septimus Heap: In Queste, Septimus is so suddenly woken up by Jenna that he does not notice the bunk above and bangs his head on it.
- Jeff does this in the Community episode "Remedial Chaos Theory" (the episode with multiple timelines). When he's confronted with a problem, he gets up to get a drink and hits his head on a ceiling fan. This ends up happening in every timeline.
- Murdoch Mysteries:
- After a seance in "Elementary, My Dear Murdoch", a skeptical Murdoch is on his knees under the seance table looking fruitlessly for mechanical tricks with Arthur Conan Doyle watching him. The psychic enters the room and says, "Have you found the hidden levers, Detect—" He straightens up and hits his head on the table, and the psychic continues, "Oh good heavens, are you all right?" Murdoch rises to his feet and says, "Fine, fine." Doyle is clearly amused, covering a smirk by stroking his mustache.
- In "The Spy Who Came Up to the Cold", Higgins and Crabtree are under a fixture at a murder scene dismantling a piece of equipment and arguing over the disappearance of Crabtree's fancy new pen. As they're trading insults, Murdoch enters and says, "Gentlemen" to get their attention and inquire about their progress. Both constables straighten up at the same time and hit their heads, effectively ending their tiff for the moment.
- The Red Green Show: Harold's first segment where he's at his new financial advisor job in the city shows him trying to get rid of his gum under his desk. When Red shows up to talk to him, Harold bangs his head on the underside of his desk.
- M*A*S*H episode "There's Nothing Like a Nurse" sees part of the cast take cover in Henry's office upon hearing an air raid siren. When Radar checks out the window, he reports that the plane in the air is none other than the inept bomber known to the camp as "Five o'Clock Charlie". Henry, hiding beside his own desk, rises to express his outrage only to crack his head on the pull-out panel he frequently uses as a foot rest.
- The Amazing World of Gumball: "The Origins" has Gumball communing with the newly-gotten fish under the kitchen table. It is there that Gumball deduces that the fish is intelligent, at which he jumps for joy. Naturally, Gumball knocks his noggin on the table's underside. When the fish tries to speak to Gumball, the excited kitten is ready to jump for joy again, but this time, dons a helmet before doing so.
- In the Darkwing Duck episode "Time and Punishment", Gosalyn is looking around a horrific alternate St. Canard when she happens upon Launchpad fixing a taxi. She calls to him, causing him to spring upnote and strike his head on the undercarriage of the taxi.
- My Little Pony: Friendship Is Magic: In "Hearthbreakers", Applejack is looking for the obsidian stone Limestone Pie has hidden somewhere in a crystal mine with a low ceiling. She clonks her head from straightening up too fast when Pinkie Pie calls for her attention.
- A variant of this theme happens with chefs and bakers who work with pizza ovens, or bread-baking ovens where the shelves are spaced closely together and the oven is comparatively deep so that the attendent has to reach deep inside it, even with the handy flat spade to get underneath the pizza tray. It is easy to graze your knuckles on a hot surface whist doing this. The natural reaction when burning the back of your hand on the roof or upper shelf of a hot oven is to snatch it away quickly in the opposite direction. Unfortunately if it's a pizza oven, the floor, or the next shelf down, are inches away — and just as hot. So you then burn the other side of your hand on the floor of the oven and snatch it away in the opposite direction.... Every novice working with this sort of oven does this at least once, to the great amusement of old hands.