This isn't exactly the best music in the world but there's a creator named "oneboredjeu" on youtube. He mixes two songs together that don't seem like they should go together at all. The end result is super fun to listen to, and this guy should be way more popular.
My favorite of his songs: "X Gon Give It To Ya Maybe" is a mashup of "X Gon Give It To Ya" By DMX (rip) and "Call Me Maybe" by Carly Ray Jepsen:
Other great songs of his include:
The Lone Slim Shady: A mashup of "Lone Digger" by Caravan Palace, and "The Real Slim Shady" by Eminem.
Thomas Writes Sins Not Tragedies: A mashup of "I Write Sins Not Tragedies" by Panic! At The Disco, and the Thomas the Tank Engine theme
Mr. Brightside at Gravity Falls: A mashup of "Mr. Brightside" by The Killers, and the Gravity Falls theme.