jumm, v. — Green’s Dictionary of Slang

jumm v.

[abbr. jumble v., but note dial. jum, a sudden jolt]

to have sexual intercourse.

1653

Urquhart (trans.) Gargantua and Pantagruel (1927) I Bk II 341: How much the more honourable and execrable they were [...] otherwise the devil would not have jum’d them.

In phrases

go jumming (v.)

to have sexual intercourse.

1890–1904

Farmer & Henley Sl. and Its Analogues.