Green’s Dictionary of Slang

1. (US gay) to have male homosexual intercourse.

1972

(con. 1930s–40s) B. Rodgers Queens’ Vernacular 108: Hobo slang (kwn ’30s & ’40s) The actual fucking of another man was called bunking up, jungling up (? fr sl jungle = hobo camp) or playing hide the sausage.

2. to have casual intercourse, irrespective of sexuality.

1964

J. Orton Entertaining Mr Sloane Act I: Too much of this casual bunking up nowadays.