Term used in the twitch chat of competitive overwatch streams. It describes people who say dumb things in chat thinking their an expert in the game, but actually don't know what they're talking about. The term makes reference to the platinum rank in overwatch, a rank where there is a stereotype that players think they're better than they actually are.
Plat Chat: C9 LUL Other Viewer: Not a c9 plat chat
Pussy that is so tight and fabulous, it's beyond lined with gold. It is short for "platinum lined" pussy. It is known to keep the man coming back for more, like a pussy hex.
"Oooh that pussy was plat-plat, I just couldn't keep myself from comin back fo mo."
"Stomach on flat-flat, and yo, pussy on plat-plat"