A jumpie is an adjective used to describe someone who has a compulsive need or used to have a compulsive need to buy jumpers. Having owned or owning 15 or more jumpers suggests that you have such an 'addicton'. The word is a hybrid of the words jumper and junkie. This adjective can be altered in order to describe an addiction to any form of clothing. This particular word is also used to describe someone who in essense believes themselves to be the deity i.e. 'Jumped up'
You've got so many jumpers you're on the verge of becoming a jumpie.