Definitions for jumped-up
Random House Webster's College Dictionary
Origin of jumped-up:
(British informal) upstart
Describes a person who thinks or acts as if he/she is superior in some way that the speaker disagrees with. For instance, pretending to be of a higher class or having greater authority than he/she has in reality.
2007, Nov 27. Scott Murray, writing in Guardian Unlimited. Stuttgart 3-2 Rangers