as a destination where you knock something or someone, American English slang, by 1835; considered by OED to be a corruption of western England dialectal collyweston, name of a village in Northamptonshire ("Colin's West Farmstead") that somehow came to signify "askew, not right." But Farmer calls it an Americanism and goes in for it as an "indefinite superlative," and DAS also does not consider the obscure English term to be the source. Early nautical references suggest it might simply be what it looks like: a sailor's generic way of indicating something has been thrown pretty far by impact.
"Matter? why d--n my old shoes, Captain Williams, here is one of that bloody Don Dego's shot gone right through the galley-door, and through the side of the big copper, and knocked all the beef and hot water galley-west. ..." [N.Ames, "Old Sailor's Yarns," New York, 1835]