1. The result of two family members, typically a brother and his hot cousin, getting together and doing the DO.
2. Neko's boyfriend.
3. The term used for the offspring of 2 dumbfucks that are closely related that are ugly as hell.
"Neko's boyfriend is an incest baby lacking an off button."
"We're gonna have an incest baby."
"Mama, I'll stay home and take care of our incest baby, I promise!"