Green’s Dictionary of Slang

(US) sexual intercourse.

1963		J. Blake letter 5 May in Joint (1972) 209: I had a brief tussle with a second-cook here [...] we swung sackwise for a blazing fornit, but no mo.
1999–2001		quinnelk T. Rex’s Guide to Life 🌐 Okay, since people don’t want to actually say the m-word and the chicken and monkey phrases have been used to death on MTV, I thought it would be my duty to provide you with a bevy of other useful terminology that may be helpful in this area: [...] a tussle with Russell the love muscle.