On a disc that has a multi-groove, whether the listener plays the main track or the hidden track depends on where the stylus is cued.
The most frequently cited example of a multiple-groove record is Monty Python's infamous "three-sided" Matching Tie and Handkerchief album, issued in 1973.
Another memorable example of a multiple-groove recording was the 1980 flexi disc entitled It's a Super-Spectacular Day issued by MAD magazine.
[1] The disc played a standard introductory section about the start of a wonderful, "super-spectacular" day, then produced one of several different comedic "bad" endings to that day, involving such topics as alien abduction, zits, street violence, and the horrors of a visiting mother-in-law.
Other uses to which multiple-groove recordings have been put include various games (such as horse races or mystery games) where the outcome is determined by which of the record's multiple grooves is played.