Acronym for Figment Of Imagination. Something that happened that truly couldn't have been real due to extremes of audicity and absurdity. Commonly used to refer to events or people. Sometimes described as a dreamlike occurrence.
Person 1: Did you meet that crazy cat Jithin last night? The one that had the one-piece jump suit and clip on earrings and was snap dancing to Soulja Boi??
Person 2: Oh shit, bro! I coulda sworn he was a FOI!!
FOI = Found On Internet. This is a standard response to someone asking where you found a picture, video, or the like; especially when you don't *actually* recall where you found said item.
A Foi Boy is an asian guy who is very insecure about non-Asian guys dating asian girls. It dominates his thinking. And he is mad that Asian women would date outside of their race.