Especially since, having ROARED out all the filthy vulgar language he can think of, he says "tits" in a completely normal, even polite voice.
From the same scene: "Defecation flows trippingly from the tongue."
Lionel: Surely a Prince's brain knows what his mouth is doing.
Bertie: You're not acquainted with any royal princes, are you.
At the very end of the movie:
Lionel: You still stammered a little on the 'W's
Bertie: I threw a couple in there, so they'd know it was me.
Lionel asking Bertie to swear more crudely.
Lionel: Do you know the F-word?
Lionel: Oh, Bertie.
Both scenes in the elevator.
Bertie doing his exercises... with his wife sitting on top of him.
Lionel: And up goes Her Royal Highness... And down goes Her Royal Highness...
Elizabeth's reaction to the whole situation is chuckle-worthy too - she is entirely unruffled.
When Lionel tells Bertie to try singing, since he doesn't stutter when he sings to Camptown Races' tune:
Bertie:You're bark-ing up the wrong tree now, Doc-tor, Doc-tor!
Logue and Bertie's first meeting:
Lionel: When speaking with a prince, one waits for the prince to choose the topic.
Bertie: Waiting for me to … commence a conversation, one can wait a rather long wait.
If Logue is talking and it's not heartwarming, it's usually one of these.
The whole bedtime story, especially:
Albert: And do you know what he turned into?
Daughters: A handsome prince!
Albert: A short-tailed albatross.
The scene with Logue and his two youngest sons, where he's reciting Shakespeare. It reminds this troper so much of herself, her sister, and her father on a normal evening at home... minus the Shakespeare.
The final rehearsal, in which Bertie brings out almost every technique he's learned to get his speech across.
In this... grave hour, fuck fuck fuck, perhaps the fateful in our history, bugger shit shit, (singing) I send to every household of my... (normal) a peoples, both at home and overseas... this message, (to the tune of Camptown races) dooh-dah, spoken with the same depth of feeling, dooh-dah-day (normal) to each one of you, as if I were able to shit FUCK BUGGER cross your threshold and speak to you... bloody well heard, bloody well heard, bloody well heard, myself! (Moving around the room, singing to the tune of the Sleeping Beauty Waltz) Foooor theeeee second time in the lives of most of us, we are...
The final speech: if for no other reason than it's Beethoven playing over the speech. The very German Beethoven, whose music Hitler co-opted for the Reich, playing over the very British milieu. Doubles as a very low-key, very epic Take That.