Green’s Dictionary of Slang

coffee stalls n.

the testicles.

1978		Maledicta II:1+2 (Summer/Winter) 118: He gives us several terms for [...] balls (coffee stalls, orchestra stalls, and flowers and frolics, as he has it for bollocks).
1980		Maledicta IV:2 (Winter) 196: Rhyming slang has many terms for these berries and we hear ‘He hit me in the orchestra’ = orchestra stalls = balls, or coffee = coffee stalls.
1998		C. Fitzpatrick ‘Gower ’98’ on Sussex University Canoe Club 🌐 I don’t recall having my coffee stalls dog and pupped by Mark and Thom.