Hey what does rumpnissan mean?

heard a danish person who kept saying it the other night..stuck in my head and cant get a translations..im presuming its slang for something??

any guesses from the Danes out there??

thanks
chanks

It means nothing that my husband and I are aware of and he is danish.

How was he using the word in what sort of sentance?

talking about girls i think..in a kind of flirty way if ya get me..?