E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Cap and Bells.
Wearing the cap and bells. Said of a person who is the butt of the company, or one who excites laughter at his own expense. The reference is to licensed jesters formerly attached to noblemens establishments. Their headgear was a cap with bells.
One is bound to speak the truth . whether he mounts the cap and bells or a shovel hat [like a bishop].Thackeray.