When a girl has a wallet, phone, pack of cigarettes, etc. in the back pocket of her tight-fitting jeans, thus causing an odd protrusion from her butt.
Jamie: Man, if that girl is gonna wear such tight jeans she better upgrade to a smaller phone!
Christina: Yeah, shes got some seriousss lump ass!
Christina: Yeah, shes got some seriousss lump ass!
by Nathan T April 01, 2008
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