The punchline of the two-verse comparison: the man who deceives his neighbour and then dismisses it as 'just a joke' is as dangerous as the madman in verse 18. The casualness of the deceit — the 'Am not I in sport?' — makes it worse, not better. Claiming it was fun does not undo the fire and arrows of dishonesty.
Memory phrase: Lying is never a joke.
Talk about it: Why is 'I was just joking' not a good excuse for lying?
Prayer: God, help me never hurt others with lies.