I made and received a lot of mix tapes in high school, and even college. Because of this, I will often hear a song and feel like it should be immediately followed by a particular song.
When Def Leppard's Pour Some Sugar On Me ends, I expect to hear the opening chords of AC/DCs You Shook Me All Night Long.
Dusty Springfield's Son of a Preacher Man should come right on the heels of Aretha Franklin's Think.
Jungle Boogie should lead into One Way or Another.
The Muppets' singing Coconut should always be followed by Jethro Tull's Songs From the Wood, of course.
What songs do you have permanently glued together in your brain?
Mix Tape, from Avenue Q