Pink Elephants

The Pink Elephants are hallucinations that Dumbo and Timothy Mouse have after drinking the champagne that the clowns accidentally drop in Dumbo's water bucket in Disney's 1941 film, Dumbo.

Dumbo
During the film, the clowns Dumbo has worked with are changing into their casual clothes and celebrating a successful fireman act with champagne. They come up with a plan for their next act, and while they are leaving to tell their boss, one hits the table with the bottle of champagne into Dumbo's water bucket, which is right outside their break tent. Dumbo and Timothy drink the spiked water ; Dumbo blows some bubbles, which transform into elephants and they start to hallucinate that these elephants are moving. These colorful hallucinations dance around and scare Dumbo and Timothy. Eventually, the effects of the champagne wear off and the elephants fade away.

House of Mouse
The Pink Elephants appear in several episodes of the series.

In the episode "Mickey and Minnie's Big Vacation", while Donald and Daisy are in charge of the club, they book the Pink Elephants as one of their faulty acts (along with 101 Dragons). They cause several inconveniences to the guests, such as acting as a canoe for Pocahontas, being weights for Hercules (eventually causing him to fall through the floor), drinking Clarabelle's milk, knocking Timon into Goofy's dirty dishes, throwing Ursula on top of Goofy, stealing Pooh's honey (which makes sense because elephants are essentially the same as heffalumps) and, of course, frightening Dumbo. Fortunately, Timothy was able to get rid of the technicolor creatures by scaring them away with a wooden sign that had the word "Boo" written on it.

Disney Parks
The Pink Elephants appear in certain shows at the Disney Parks.

Animagique
The Pink Elephants are the first set of characters Donald Duck encounters in the show. When they first appear before him, they perform a shortened version of the original Pink Elephants song. After this, Donald thanks them, and watches them exit.

Fantasmic!
Pink Elephants appear in the Disneyland version of the show, dancing to their song.

Trivia

 * The Pink Elephants musical number is very controversial due to the inclusion of alcohol and drunkness.
 * A Pink Elephant made a cameo on the Simpsons where it crushes a goblin hallucination Barney was experiencing that was caused by a peyoti-laced organic drink. Afterwards, Barney thanks it and claims that it's always been there for him.
 * Part of the Pink Elephants' parade was heard playing on T.V. in Disney's 2007 film, Enchanted.