Refusing to being called sir because you don't think your better than others.
While the trucker was being hassled by a cop that sarcastically addressed him as sir, the offended driver invoked sir-rejection and said, "Don't call ME sir, I work for a living."
When a user submits a new word and definition to Urban Dictionary and the volunteer editors who happen to review the submission lack intelligence, understanding and/or a sense of humour therefore end up prematurely rejecting spectacularly humorous submissions.
Editor - "A few volunteer editors read your definition and decided to not publish it. Don't take it personally"
Disappointed user - "Damn it, premature Rejectulation again!"
guy #1: urban dictionary rejected my definition for "George Tabuki"
guy #2: you should just post those urban dictionary rejected words on unurbandictionary.blogspot.ca
guy #1: I definitely will.