STEVE: (at the furniture store; holds up a decorative furniture pillow) What — is this?

SUSAN: It’s a cushion.

STEVE: Right! Yes! It’s a cushion! Thank you for that, very informative. (to Jeff) Have you got any of these?

JEFF: No.

STEVE: Of course you haven’t. (to clerk) — You. You married? Living with anyone?

JUNIOR SHOP ASSISTANT: No.

STEVE: Got any of these?

JUNIOR SHOP ASSISTANT: No.

STEVE: Of course not! Okay. (looking at Susan and her female friends) You bring these things into our homes. They sit on our chairs. They watch our televisions! Now, I just need to know, on behalf of all men, everywhere — I just need to ask, please, what are they for? I mean, look, look at the chubby little bastards, just sitting around everywhere. What are they? Pets for chairs? (to senior clerk) Come on, you sell them — what are they for?

SENIOR SHOP ASSISTANT: Well — you sit on them.

STEVE: Aha! I see! That’s where you’re wrong! Nobody sits on them. Ok, watch this! Here’s the cushion. I’m putting it on the sofa. Now, watch me! I’m sitting down, and what do I do on my final approach? I — (he moves the cushion from the seat) — oop! — Move the cushion! You see? It’s not involved! It’s not part of the whole sitting process! It just lies there. It’s fat litter! It’s a sofa parasite!

JANE: It’s — you know, padding.

STEVE: Oh, padding! Oh now that’s interesting. See, I like padding. You know, if I was, say, an American football player with all those big bastards running at me, I would say, you know, “Give me some of that padding and be quick about it!” You know, if my job involved bouncing down jagged rocks, I would say, “In view of those jagged rocks down there, I’ll have some of that padding, thank you very much!” But Susan, Sally, Jane, this — is a sofa. It is designed by clever scientists in such a way so is to shield the unprotected user from the way of skin abrasions, serious head trauma, and of course — (he dives behind the sofa and reemerges) — Daleks! You lot trust me, girls, trust me on this one, you do not need padding to tackle upholstery! So please, once and for all, tell me, why on Earth you would want me to sit on one of these?

SUSAN: Because, if you pressed it firmly against your bottom it might stop you talking!

Steven Moffat (b. 1961) Scottish television writer, producer
Coupling, 02×03 “Her Best Friend’s Bottom” (2001-09-17)
    (Source)

(Source (video); dialog confirmed.)