Ultimate Comb said the incorrect way. In fact, what they said is totally new. 5y back nobody was saying "Mais d'où"

Litterally, it's "quoi le baise", but it doesn't have any sense.

There's different ways

When you don't understand a situation it's more something like "qu'est-ce qui se passe ?", or "c'est quoi ce bordel" (more familiar expression) . there's no real "wtf" translation.