jack·a·napes 
(jăkə-nāps′)
(jăkə-nāps′)n.
1. A conceited or impudent person.
2. A mischievous child.
3. Archaic A monkey or an ape.
[From Middle English Jack Napis, nickname of William de la Pole, Fourth Earl and First Duke of Suffolk (1396-1450), probably ultimately from alteration of ape, monkey, ape (because his coat of arms depicted a chain and clog of the kind used to tether a pet monkey).]