On some shows, this is done routinely and serves to enhance the overall wackiness, on others it is used sparingly and to make a specific auditive point or gag, for example when the impact of a huge object fails to produce the ear-shattering KABOOM sound the audience expects. Typically, 'big' things get a 'small' or silly sound, but the trope works the other way around as well. Stock Sound Effects and inherently funny sounds (associated with circuses and clowns) are especially popular. In a common variation, this trope is Exaggerated by the use of a different Wacky Sound Effect every time an action is repeated, for example when a character is repeatedly hit on the head with the same object.
Sometimes, a sound is played where there shouldn't be anything to hear, for example Squeaky Eyes (a subtrope). Contrast with Audible Sharpness and Audible Gleam which aren't considered wacky but rather cross over to Coconut Effect territory. Contrast also with Space Is Noisy, where 1) the space noise is also more or less expected by the viewer and 2) the sound effects are pseudorealistic rather than wacky. See also Editorial Synaesthesia.
Another extreme version of this is when something or someone gets a sound effect for just being there or coming into view.
Wacky sound effects are a staple of animation, but also sometimes used in older live-action works where it is likely, however, to be deemed by a present-day audience to feel inappropriate and tantamount to Special Effects Failure. Then, there's the connection to Slapstick and, by association, to funny home videos.
- After Ultra Fast Pony's first two episodes conspicuously lack any sound effects, the third episode, titled "Now With A Sound Effect", has the characters admiring the use of an overly loud apple-biting sound. The rest of the show follows the precedent, using loud and unfitting sound effects whenever possible.
- The Man with the Golden Gun features a visually impressive Ramp Jump car stunt which is accompanied by a silly cartoony slide-whistle sound.
- Many fans were very upset that one of the most spectacular car stunts in film history was essentially ruined this way, effectively sabotaging the entire chase scene of which the stunt was part. The scene is thus often considered to symbolize everything that many considered wrong about the 1970's Bond films.
- In Star Trek III: The Search for Spock, the sabotaged U.S.S. Excelsior's engines fail with a sound effect that resembles a stalling car.
- In the movie Airplane!, this was coupled with Just Plane Wrong as in-flight shots outside the airliner were accompanied by the sound effect of prop aircraft.
- Not to mention the sound of a steam locomotive as it pulled away from the airport terminal.
- The Swedish cult slapstick comedy Drömkåken (The Dream House) has a few, including a fuse box that makes a cuckoo sound after it short circuits, and a washing machine that, spazzing out due to said fuse box breaking, breaks down with a burp (followed by the laundry falling out as if vomited).
- In Mom and Dad Save the World, two guards, on orders from Spengo, shoot themselves in the head for their stupidity (they gave him a opinion on facial hair that he did not like). When the do this with their quirky ray guns, one can hear what sounds like a rubber duck being squeezed.
- In Repo! The Genetic Opera, during the song "Thankless Job", several wacky sound effects can be heard.
- Monty Python's Life of Brian had a spaceship (yes, a spaceship) that made gearshift noises while in space.
- In Ayoy Dr Jekyll And Mr Hyde Johann's duster sounds like a vacuum cleaner. Other characters tell him to stop dusting while they're trying to have a conversation.
- One gag in Robin Hood: Men in Tights has the (12th century) messenger fox scurry off into the woods to the sound of a ricocheting bullet and... a dolphin cry?
- The Three Stooges punctuated their slapping and hitting with overdubbed sound effects that often did not actually reflect what the real sound would be, such as the sound of a bass drum when someone (usually Curly) is hit in the stomach.
- A (probably) unintentional example. In Frankenstein 1970, the disposal unit Victor uses to get rid of body parts makes the sound of a flushing toilet. Originally, it made a grinding noise but the studio decided it was too gruesome and changed it. They probably went too far the other way, as the new effect caused audiences to laugh.
- Sim Farm gives us some truly bizarre sound effects. Watch this guy's reactions to them (starting at 1:43).
- Joke weapons in SoulCalibur II produce Wacky Sound Effects every time they connect: Astaroth's Rock trumpets like an elephant, Yoshimitsu's Shepherd's Crook bleats like a sheep, Necrid's Ethereal Edge makes a "boi-oi-oing" noise, Nightmare's Galley Oar makes a sound like breaking waves, and so on.
- The weapons in Worms games sound wacky — because they are.
- In The Ring: Terror's Realm, there's a wacky "SppplllAAAAT" sound effect used throughout the game (it's even used on the menu screens).
Spoony: That was the best sound effect they could come up with, the sound of someone stepping on a mustard bottle.
- In Neverwinter Nights, searching a pile of rocks, or other such rubble, would occasionally be accompanied by a slamming door sound.
- In a Garry's Mod video called "Mass Defect" created by Kitty0706 involves one of two "fancy" Servant Grunts from Amnesia: The Dark Descent saying "Fregley, get into character quick!" Immediately afterward, a Wacky Sound Effect along the lines of "BAP" plays, they lose their top hats and monocles, and they proceed to growl like zombies and chase after the "protagonist."
- The Ren & Stimpy Show was a major Trope Codifier for this in animation. For example, Ren slapping Stimpy will be accompanied with sound effects like glass shattering or bowling pins being knocked down.
- Invader Zim had this in spades. The sound of air slowly being let out of a balloon was often used for when stupid people were straining their brains.
- Ed, Edd n Eddy reveled in using deliberately inappropriate sound effects, such as microphone feedback for when Eddy's hand gets a cactus stuck on it or semi backing up when Double D awkwardly motions himself away from Ed. It even delighted in using some seen (almost) nowhere else, such as the iconic "SUBALUWA!"
- Rocko's Modern Life also loved this trope, often having such sound effects be randomly heard or used for inappropriate situations (very much like the above-mentioned Ed, Edd n' Eddy.) This became especially prevalent in the third and fourth seasons, when Jeff Hutchins was the sound effects editor.
- Done regularly in Looney Tunes cartoons - a gunshot sound for a slamming door, for instance.
- Used for a specific gag in Duck Amuck when Daffy (now drawn as a country western singer) requests that the trolling animator add some sound to the cartoon, only to have a machine gun instead of a guitar chord, a donkey bray for when he smashes said guitar and random jungle noises when he tries to yell.
- SpongeBob SquarePants has lots of illustrative sound effects to enhance the physicality of the characters: SpongeBob has both 'woody' (when his arms break off) and 'spongy' (when he walks) sound effects. Also, his facial expressions are quite noisy.
- All spaceships in Futurama seem to be fitted with horns.
- Drawn Together has lots of these, with Wooldoor Sockbat as the epicenter. His masturbation technique involves a long string of Wacky Sound Effects.
- Xiaolin Showdown does this most often with random, small fart noises during a dumb or stupid scene. When Dojo drinks several bottles of hot sauce in one episode, he belches out a huge column of soot, and a split-second fart sound is played.
- In Aladdin, when Iago hits Jafar in the head it makes a sound that no man's head being hit by a parrot's wing should make. It sounds a little bit like hitting a washing machine.
- At the end of most of Hanna-Barbera's Ricochet Rabbit and Droop-a-Long Coyote cartoons, Ricochet zips off into the sunset, ricocheting off boulders, plants and things with the sound of "pings", "zings" and gunshots. When his deputy, Droopalong Coyote, tries it, he gets sound effects of clanks, thuds and crashes.
- Interestingly enough, Discord from My Little Pony: Friendship Is Magic tends to have a subtle version of this played it for drama. In his initial appearance, his every footstep was accompanied by a random noise, and in the season four finale there was the occasional out of place squeaking as his magic was drained from him. Then again, he is a spirit of chaos, so it makes some sort of sense...
- The "squeaky dog toy" sound effect that accompanies a forced smile.
- Freakazoid! features one in Toby Danger: when something collapses, explodes, or otherwise goes horribly awry, the sound effect used is that of a flushing toilet. Lampshaded for laughs near the end of the short when water comes cascading down. Potentially toilet humor.