Fake snippets made out of acapellas of other songs. It happened with I Need a Doctor pt. II, Running Away, an untitled song with Kendrick Lamar, Dark Corners, Off the Wall, and most recently, a song with Ca$his featuring Eminem called You Can't Compete.
If you hear a less than 20 second snippet, that is mostly beat, and sounds somewhat snipped together, then it's definitely fake.