Monty Python's Matching Tie and Handkerchief Album. Not only did it "fool" you into thinking that the album included an actual tie and handkerchief with the album being the special free prize (I don't want to give away the spoilers), but the album contained two concentric grooves on side 2. So when you dropped the needle on Side 2, you never knew which set of skits were going to play.

The got the idea from carnival games of chance. One of the game was a horse race, and you would bet on the winner. The horse races were announced on records with concentric grooves, so the runner of the race wouldn't know which horse would be the winner. It would be a different outcome every time.