This actually appears in the trailers of the movie. Adam Sandler, as Little Nicky, displays a Chicago album cover, plays a song from the album forward, then backward to reveal a hidden message. The album he displays is Chicago 5, the "Woodgrain" album, on which the most familiar song is likely "Saturday in the Park." The song he plays is "Does Anybody Really Know What Time It Is," which is actually on the first Chicago album: Chicago Transit Authority.
Talk about advertising your mistakes!