You could always get a friend to bid at 15% below ask the week before you offer 10% below ask. One of my friends is a permabear, and gets his giggles by making ~25% off bids.
And for what it’s worth, we got our first choice house offering 7% under ask. The sellers countered halfway, and we said, no, our first bid was a firm offer. Their agent called us back to accept a half-hour later.
