That's a guarantee

Welcome to my Furniture Store. Would you like to see the great furniture here? There's a couch for sale, and a bed. This furniture is very good. I guarantee you'll like it. I'm so sure you'll like it, that if you don't, I'll murder my wife. I'll beat her up, I'll push her down a flight of stairs, I'll strangle her until her eyes pop out. That's my promise to you if you don't like this furniture.

I'll do it. I will I will I will. Tell me you don't like my furniture and I will. I'll run her over with my car and leave her for dead in a ditch. If she's still squirming, I'll pull over and I'll brain her with a crowbar. Because I sell furniture.

Look at this table. It's a piece of shit. The legs are crooked, I hit it with a hammer a bunch of times, that's why it has all these dents in it. But seriously, buy the table, because you'll like it, probably. If you don't, I'll kill my wife to make it up to you. I'll even throw my infant twins in the deal, I'll kill them to. I'll lock one in a hot car and split the other one's head in half with an ice pick. You'll like the table, though, so I won't. I won't do it. I won't.

NO. NO NO NO.

Here, I'm going to sell you this chair. I found it in the trash and dragged it to my store. It has a putrid stain on it. I'm going to tie it to the roof of your car and sell it to you right now. Gimme your wallet you little shit, this chair costs a hundred dollars. No, fifty. I don't care, just gimme your cash, I'll give you the chair then I'll go home and kill my wife. I mean, if you don't like it. I'll kill her in front of you, if you want, just don't tell the police where you got this sweet deal.