Green’s Dictionary of Slang

get off at... v.

also get out at...

[1970s+] used in terms meaning to perform coitus interruptus, to withdraw well before ejaculation; specific usages are usu. regional but can be found further afield.

In phrases

...Edge Hill (also ...Broadgreen) [Edge Hill is the station before Liverpool Lime Street] [1980s+]
...Gateshead [Gateshead is the railway station before Newcastle-upon-Tyne; note RN use get off at Fratton in which Fratton is the stop immediately before Portsmouth dockyard] [1980s+]
...Green Island (also get out at Green Island, get off at Papakura) [Green Island, the station before the terminal at Dunedin; Papakura is a couple of stops prior to the terminal at Auckland] [2000s] (N.Z.)
...Haymarket [used by the natives of Edinburgh, where Haymarket is the railway station immediately before the terminal Edinburgh Waverley] [1980s+]
...Hillgate [a notional place, poss. playing on hill = the mons veneris, and gate, i.e. the entry to the vagina] [1970s]
...Paisley [used by Glaswegians, where Paisley is the railway station immediately before Glasgow] [1980s+]
...Redfern [Redfern is the railway station immediately before Sydney Central] [1970s+] (Aus.)