When someone is said to "need a cheeseburger" it means that the person is way too thin - so much so that the person doesn't look attractive. The implication is that the person is anorexic / dieting too much and needs to put on some weight. Almost always said about a female but a male isn't immune.
"Damn, did you see how skinny Angelina Jolie looked at the Academy Awards the other night? That girl needs a cheeseburger!"

"LeAnn Rimes looks anorexic. Someone please give her a cheeseburger!"
by kayemmdee March 18, 2012
Get the needs a cheeseburger mug.