s/foo/bar/ is an idiom which means "I didn' t mean to type ' foo' , I meant to type ' bar' ". Its use in talk systems, especially irc, comes from the use of s/// as a substitution operator in Perl, sed and ed. In these languages and tools, s/foo/bar/ would replace any substring matching the regular expression "foo" with the string "bar". (1997-03-16)
