A friend that you’ve known since the infancy or a childhood friend that you’ve known your entire life, essentially since the time you we’re both fetuses, because your mom and their mom and/or parents have been friends since before your birth and you became friends with your parent’s friend’s child by default.
by Fetusfriends101 June 14, 2019
2 or more friends who are unconditional best friends from birth, who know each other inside and out. they're usually kind of annoying
those two are fetus friends
by Adam Henaghan August 19, 2007