Pretty much every minute that guest-stars Hugh Laurie or Stephen Fry are on-screen in "Fry And Laurie", but especially when they finally meet at the end of the episode.
Inspector: Why are you stopping us?
Security Droid: All patrons at Solar Meadows Sanatorium must discard footwear before entering Solar Meadows Sanitation Ward. Risk of tracking foreign particles indoors must be contained. Do not worry- we have installed top-quality artificial lawn carpeting so that your lack of footwear is made accommodating.
(Joanna grins cheerfully and begins unlacing her tennis shoes)
Inspector: Oh, that's right. You had a field day after that one Intra-Majorian tracked in radiation from the trenches of Marzipan. But it would look rather undignified to go shoe-free. So I brought regulation-meeting booties for myself. Got a buy-1-get-1-free deal, so there's enough to spare.
(puts on one set of booties and extends his hand to Joanna with the other set)
Joanna Martin: What, you gonna put those on your hands or something?
Inspector: Of course not! They're for you!
Joanna: I'll pass, thanks very much!
Inspector: May I ask why?
Joanna: Grew up in the Gloucestershire countryside, full of lush green grass. I explored the fields almost everyday from spring 'til early winter, rain or shine. My dad said I'd get grass stains on my shoes, so I always went barefoot. Loved how the grass caressed against my toes. I felt so carefree, like I could wander the whole world. Since then, shoes just annoy me, because they feel so uninviting for wandering. Heck, I hate shoes. They're so stuffy and sweaty. And the fact we're by the Sun of all things... they're like frying pans for my feet. They're comin' off and the toes are goin' in for a landing on that faux-grass! When I see Astroturf carpets waiting for me... I can't resist.
Inspector: You really sure you don't want the booties?
Joanna: Nope! They say intelligent people are practically allergic to shoes. I think I look brainier in my bare feet.
(kicks off her shoes and they crash to the floor with loud thumps)
Joanna: And now for these stinkers- Adios!
(Flicks her socks away)
(Wriggles her toes in the Astroturf)
Joanna: Ahhh! So much cozier! My dogs are in paradise!
(Patters down the halls barefooted)
Joanna: Yeaaaah! Shoeless by the Sun!
Inspector: So this is the Booth.
Joanna: Not much to look at inside, is it?
Inspector: Oh, you haven't seen the hidden rooms, yet.
Joanna: What, there's more?
Inspector: Yep! I have to disguise the Booth's interior so nobody learns what's really inside if they stumble into it by accident. Once I pull this lever, a whole six dozen or so rooms will open up.
Joanna: And what kind of rooms are they?
Inspector: Whatever you want them to be. They assume their appearances based on how you picture them.
Joanna: (beams) By any chance, could I make a giant room full of grass appear?
Inspector: Go for it! (pulls lever)
Joanna: Really? Ehehe! Forget these! Never gonna need 'em! (strips off her shoes and socks again)
(stubs her toe on the corner of the Booth's interior)
Joanna: Yeow! (clutches foot) Hey! What gives! I should be barefoot in a wonderland of grass right now!
Inspector: About that... The Booth only has one room.
Joanna: ...Seriously? You lied?
Inspector: Have you not been paying attention? I said the Booth has rooms based on how you picture them... as in your imagination.
Joanna: (sarcastically) So in other words, you got snubbed on the luxury suite?
Inspector: In other words, Miss Joanna Martin, travelling through space and time is dangerous. You can't just go gallivanting off unshod! Remember how you almost branded your soles on the scalding hot gantry of the Sanatorium when it floated too close to the Sun? As long as you're in my company, you better follow my dress code. And that means shoes required, on my ship, and all other walks of the universe.
Joanna: Fine, fine! (unethusiastically replaces footwear) But if I have to wear those stupid coke bottle specs, I'm painting this whole thing purple just to spite 'ya. I adore the colour purple. The eye-searing red is paining my irises worse than the blinding Sun did!
Inspector: They are not stupid specs!