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Beverly and Deanna enjoy themselves in the disco setting of program Crusher 54

Crusher 54 was a holodeck program used by Beverly Crusher on the holodecks of the USS Enterprise (NCC-1701-D).

Given the name and user, the program was presumably created by, or commissioned for Beverly Crusher.

The setting of the program was the Bridge Club, a disco in Brooklyn circa 1975. The club ran dance competitions which Crusher participated in with her holographic partner Mikey. Another character in the program was Carlos, a notoriously sleazy patron of the club.

Crusher enjoyed the program for the disco dance, more freestyle then her usual tap or jazz, and the good exercise she got in the process. In 2368 she invited Deanna Troi to join her in the program. (TNG comic: Captain's Pleasure)

The name "Crusher 54" is apparently a reference to one of the most famous disco clubs of the era, Studio 54. The Bridge Club and its Brooklyn location are patterned after the setting of Saturday Night Fever, the most famous disco movie of the era.