Toast can either be the answer to a question or a nonsensical response to a weird statement. It basically means, "I don't understand what you just said or why you said it, but whatever floats your boat."
Person 2: "Toast?"
Person 1: "I'm so pretty. Don't you think so?"
Person 2: "Toast."
Toast (v) the act of inhaling the combustive vapors of the cannabis plant
2. that's some real bombass toast
3. That's a fat sack of toast