A synonym and/or substitute word used to describe a female with absolutely MASSIVE natural breasts. It is derived from the two Japanese root words, "Oppai"(Boobs) and "Kaiju".(Strange Beast) In layman's terms your essentially comparing a woman's bust size to that of an impossibly large city destroying movie monster, e.g. Godzilla.
Holy shit! Did you just see that chick over there; she's got some serious Oppaiju. A J cup at least!
by Ingadoohhhh May 06, 2024