Frick and Frack is for any two people who are closely linked in some way, especially through a work partnership or strong friendship.
The origin is from a famous partnership of Swiss comedy
ice skaters, Werner Groebli and Hans Mauch, whose stage names were Frick and Frack. They came to public fame in the later years of a series of skating spectaculars called "Ice Follies", promoted by Eddie Shipstad and his
brother Roy, which began in 1936 and ran for almost
50 years. Their association lasted so
long, and they were at one
time so well known, that their names have gone into the language as slang or a reference to two people who work well together or get along great.