Let's assume -- I'm not even going to bother to check -- that a "custom tailored billionaire suit" normally costs $1,000.
100% off that would make the cost of suit $0.
In the real world, with, you know, math, 800% off means they would pay me $7,000 to accept the suit.
I'm guessing that this ad is not a real-world offer. But if it is, I guess I'm getting a new suit. And a pile of money.