- When Screwtape gets worked up about the difference between Heaven and Hell, to the degree that he involuntarily takes the form of a large centipede. It becomes even funnier when read by John Cleese and ESPECIALLY Andy Serkis, who both had to pick bits of studio from between their teeth after that particular take.
- Screwtape's rants about the girlfriend Wormwood's target has—she's a good Christian and happens to be a charming and sexy vivacious young woman who's also "the sort of creature who'd find ME funny!"
- In the play version, Screwtape points out that famous people are a "good" influence, since they're always changing their minds...then tilts the book he's reading to reveal that it's a biography of Madonna. Cue "Material Girl" playing during the next set change.
- The events and letter that occur when Screwtape discovers that dear nephew Wormwood has been passing his letters and criticisms along to Hell's secret police. The frantic ass-covering that Screwtape engages in is hilarious.
- Screwtape telling Wormwood how this secret God's keeping called "love" was the cause of the falling-out between Him and Satan. According to Screwtape, God's failure to trust Satan with the secret caused him to storm out so suddenly that it led to the "ridiculous" story about him being expelled from Heaven.
Funny / The Screwtape Letters