Green’s Dictionary of Slang

bodkin n.2

[SE bodkin, a long, thin object, usu. a pin; the earliest cognate use is in John Ford’s The Fancies (1638) when it refers to the person squashed between two others in the same bed]

a person who is wedged between two others, esp. when there is room for only the original couple; thus sit bodkin or ride bodkin, for a coach passenger to ride wedged between two fellows when there is insufficient room for three abreast.

[UK]Ford Fancies Act IV: Where but two lie in a bed, you must be Bodkin, bitch-baby must ye?
Loves of the Triangles 182: While the pressed bodkin, punched and squeezed to death, Sweats in the mid-most place [F&H].
[UK]Thackeray Shabby Genteel Story (1853) 82: Carry must go bodkin; but she ain’t very big.
[UK]G.J. Whyte-Melville Kate Coventry (1865) 111: I would rather give Brilliant a good ‘bucketing’ [...] than go bodkin in a chariot.
[UK]Hotten Sl. Dict. 79: A small or young person, sitting in the centre, betwen two others, in a carriage, is said ‘to ride bodkin.’ Amongst sporting men, applied to a person who takes his turn between the sheets on alternate nights, when the hotel has twice as many visitors as it can comfortably lodge.
F. Montgomery Thrown Together II 62: The three called a hansom outside, and Cecily [...] sat bodkin .
[Aus]Sydney Sl. Dict. (2 edn) 1: Anyone sitting between two others in a cab or carriage is said ‘to ride bodkin’.