Please explain what this expression means: 'THIS BOTTLE JUST WATERBOARDED ME"
It's not a fixed expression or any sort of idiom.
Waterboarding is a form of torture where the suspect has water poured on him in such a way that he feels he is drowning. It sound like somehow the water from some water bottle spilled in such a way that it got in the speaker's face.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.