Screwtape's rants about the girlfriend Wormwood's target has—she's a good Christian and happens to be a charming and sexy Spirited Young Lady 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.