bonk v. in bicycling, to become exhausted. Also bonk out and bonking, n. Editorial Note: Eric Partridge dates this term to the 1930s in his Dictionary of Slang and Unconventional English (8e, 1984), but no citations are given. Editor Paul Beale tentatively connects it to bonk ‘a short, steep hill’; however, there seems to be no evidence to support this connection. The Oxford English Dictionary dates the noun bonk ‘(A sudden attack of) fatigue or light-headedness sometimes experienced by racing cyclists and other athletes’ to the U.K. in 1952. (source: Double-Tongued Dictionary)