Yippee Ki-Yay!

A relatively new Stock Phrase, usually delivered as a message of defiance or disrespect to an enemy or oppressor. In contexts where profanity is not an issue it is often followed by "motherfucker" in tribute to the Trope Maker; elsewhere, family- or kid-friendly alternatives are used, or the followup is dispensed with entirely.

The phrase originated as a cheer or cry allegedly shouted by Cowboys in the Old West; like many things from Westerns, it's probably completely fictional. The version seen in the trope name comes from "yippie yi yo kayah", part of the refrain from the 1936 Bing Crosby song "I'm An Old Cowhand (From the Rio Grande)". This eventually mutated in common usage into "yippee ki-yay ki-yoh", and from there lost the last two syllables. It still retained its Cowboy connotations throughout this -- which is why it became the comeback delivered by Bruce Willis's very American John McClane when called a "cowboy" by Alan Rickman's German Hans Gruber in Die Hard.

And from there, it re-entered the meme pool with a new meaning and its original cowboy connotations mostly forgotten.

Not to be confused with Yippee Ki-Yay MF, a 2007 TV show.

Examples of Yippee Ki-Yay! include:

Fan Works

In the Undocumented Features "Golden Age" story REDNECK: Die Hardly, which is Die Hard on Salusia, Redneck gets to say "Yippie-ki-yay, mother fucker!" at an appropriate moment.

Film

Alvin and The Chipmunks, Alvin is chased by a guard. When he finds a spotlight to use, Alvin shouts 'Yippee ki-Ya, Mamacita".
The Trope Maker and Trope Namer is the Die Hard series, where the entire phrase, including "motherfucker", becomes the Catch Phrase of John McClane, played by Bruce Willis.

Live-Action TV

Network broadcasts of the Die Hard films routinely censor John McClane's Catch Phrase to the inexplicable and incomprehensible "Yippee ki-yay, Mister Falcon!"
Yippee Ki-Yay MF, the 2007 TV show mentioned in the main text, clearly draws on the defiant use of the phrase from Die Hard.
Leverage: In one episode, Eliot, after beating up three mooks, gets most of it out as a Curse Cut Short:

Yippee-ki-yay, motherf- Found it!

Played with in this exchange from Two and a Half Men:

Alan: Now, I have been to a lot of these things with Mom, and I know you think it's gonna be bad, but believe me, it's gonna be worse than you can even imagine.
Charlie: You're really enjoying this, aren't you? You just love seeing me unhappy.
Alan: Yeah. I mean, did you feel sorry for me when I had to wear that cowboy outfit to her celebrity AIDS hoedown?
Charlie: That was different.
Alan: How?
Charlie: It was you.
Alan: Yeah, well, now it's you. Yippee-ki-yay, mother-accompanier.

Western Animation

In The Loud House episode, "Cereal Offender", Lynn screams the line to market shoppers while Lincoln was doing the grocery.
In Big Mouth, Monster Horrensess once tells of group of kids this, right down to "motherfucker", as she and her human partner exits the school.