[Good boy, Mulder. You've just earned bonus points from Oswald for actually having seen his cartoons at some point.]

Uh... Not really. It's as physical as a cartoon heart can be. See, when a cartoon character has a heart, it's proof that they're loved by their fans. Then, when they're forgotten, they lose that love. So they lose their heart, geddit?

Gettin' your heart back means you've regained the love of your fans and then ya can leave Wasteland. It's just hard for us classics to make a comeback once we're filed away. Cartoon shorts aren't what they used to be, ya know?