Verb; used to describe an African-American or extremely tan person whose bodies produce excess amounts of Melonin, the chemical which allows skin on the body to tan. 'Watermelonin' refers to the racial stereotype of African-American's having an overt fondness for Watermelons, thus anyone with an excessively dark complexion is said to have Matermelonin.
"See that guy there? He goes tanning so much, looks like he's got Watermelonin."
by Matthew Johnstonson January 07, 2008