A sexual technique in which you insert your middle and index fingers in the hole of your choice in a manner that resembles Nappa's Volcano Explosion technique from Dragon Ball Z
Linguistics joke. There's a fake IPA symbol to go with it, that looks like a pig snout.
It's linguistically correct description of, well, the sound pigsmake.
First-year linguistics students can be humiliated by asking them to include nasal-ingressive voiceless velar trill in their presentation of rare and difficult-to-pronounce sounds in the West African languages.
Recognized shorthand on the Usenet group comp.std.c for any unexpected behavior of a C compiler on encountering an undefined construct. During a discussion on that group in early 1992, a regular remarked "When the compiler encounters a given undefined construct it is legal for it to make demons fly out of your nose" (the implication is that the compiler may choose any arbitrarily bizarre way to interpret the code without violating the ANSI C standard). Someone else followed up with a reference to "nasal demons", which quickly became established. (see Jargon)
From the online hit "Dragonball Z Abridged" created by Team Four Star, Ghost Nappa is the awesomely hilarious poltergeist Nappa becomes after Vegeta kills him in Episode 9.
Nappa was quickly established as everyone's favorite character, and to keep him in the show, Team Four Star invented Ghost Nappa. Those clever bastards.