Paris Hilton fears her boyfriend Benji Madden is cheap

Good Charlotte rocker Benji Madden often leaves the house without his wallet.

"Benji never seems to have cash on him to pay for things and tip people, which means Paris always carries cash around," says an insider. "She feels like it's easier to throw down a hundred-dollar bill than wait for Benji to fish around for a credit card, which he probably left at home."

Benji claims he's just forgetful, but Paris, adds the source, "is starting to feel like he's cheap."

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