frick and frack, n. — Green’s Dictionary of Slang

frick and frack n.

[echoic of the sound of their knocking together; ult. Frick and Frack, the 1920s–30s Swiss comedy skating team, who performed in the US and Europe. They were famous for a routine where they would put the heels of their skates together, bend their knees and skate in large circles with their bodies leaning outwards]

(US black) the testicles.

1980

E. Folb Runnin’ Down Some Lines 198: There were also terms related to men and sex: [...] frick and frack (testicles).