Offer to sign up for a price

You decide that since you've been leading a boring life lately, you'll agree with one condition... a payment of sorts.

"First I get you and her" You decide that if you're going to be put through all of this, you might as well indulge yourself and hey, even if they disagree, you'll still be the test subject.

"Ok, I guess fair is fair" Your sister's master husband replies.

You immedietly tell them to strip and lie on the floor, spread eagled.