You take one song, add another, then lay the combined track down, and there you have a mashup. Most suck, but some are BRILLIANT.
Like the following obsessive love duet by the sunny Taylor Swift and the creepy Trent Reznor, “Shake It Off (The Perfect Drug)” (mixed by Isosine).
Then there’s the psychedelic techno hit by Jefferson Airplane and Fatboy Slim, “Somebody To Praise” (mixed by lobstermashups).
Dark, brooding Prog Rock meets the acme of Disco in “Stayin’ Alive In The Wall”, by Wax Audio.
Last but not least, Black Sabbath’s “War Pigs” smashed together with Led Zeppelin’s “Whole Lotta Lovin'” in “Whole Lotta Sabbath” (also by Wax Audio).
Whole lotta loving plus Warpig? It’s like my own personal Rock Anthem.