Found in a thrift store. The best comment from the Reddit thread: "Rick donated this after realizing that any combat advantages gained by having a small knife were immediately lost by no longer having his pants stay up."
And regarding shivs:
A shiv (possibly from the Romani word chivomengro, "knife") is a slang term for any sharp or pointed implement used as a knife-like weapon. The Oxford English Dictionary suggests shive, a razor, documented in 1915, as the root word.Composite image made from photos posted at imgur.