Green’s Dictionary of Slang

other, the n.

[note Merry Drollery (1661) ‘As much as this a man may kiss / His sister or his mother; / He that will speed must give with need / A little o’th’ t’on with t’other’]

[1930s+] sexual intercourse; esp. in the phr. a bit of the other; usu. hetero- but sometimes homosexual.