Ben Button Disease

Ben Button Disease is when a patient is born, and they mature, they actually grow "young". Basically the patient ages backwards.

Also See Jen Button Disease

Brat Pitt's character in Benjamin Button suffered from Ben Button Disease

Dude 1 : "Yo, that baby is mad smart"
Dude 2 : " Nah man, this little baby is actually 76 years old. My mom used to baby sit him but he looked mad older than my moms. People round the block thought they were just dating and shit"