This underworld slang for to kill or murder may have its origins in the relatively genteel world of British boating. The theory is that bump off derives from a rule in boat racing that disqualified any shell that was bumped into by the boat behind it. This elimination regulation was familiar to gamblers betting on the races, proponents of the theory argue, and the term passed into the lexicon of the British underworld. Neither the Oxford English Dictionary nor British slang authority Eric Partridge support this theory, simply citing bump off as an Americanism first recorded in 1910.