I have gotten better at using the internet to look things up, but the first definition of 'jumper', aside from talking about the 2008 film, is 'a person or thing that jumps', which did not make sense in this context.
Slang, however, is "a type of language that consists of words and phrases that are regarded as very informal, are more common in speech than writing, and are typically restricted to a particular context or group of people", which I'm guessing is what you meant. But did you know it also means "attack (someone) using abusive language"?