(American)

To have sex (with). This fairly inoffensive term, heard among American adolescents, began to be used by younger speakers in Scotland and the north of England in the late 1990s. Like many similar terms (boff, biff, etc.) it probably derives from the use of the same word (in this case in British dialect) to denote a jab or punch.

'You hear lads saying they just want to bob her. Not me, mate.' (Guardian, 15 July 1996)