Writing as drama then adding the humour?
Like this, you mean?
NARRATOR: it is a truth universally acknowledged, that a single man in possession of a good fortune must be getting more fanny than he can shake a stick at.
Scene: an English manor house. Int. Day.
MRS BENNET: My dear Mr. Bennet, have you heard that Netherfield is let at last?
Mr BENNET: Netherfield? No, but we all know the last mistress had her nether regions feeled plenty of times. Before they sacked the gamekeeper.
MRS BENNET: Do not you want to know who has taken it?
(CLOSE-UP ON MR BENNET WHO LOOKS LONG-SUFFERING AND THUS INJECTS HUMOUR FROM CHARACTER)
MR BENNET: Go on then, spit it out - as the gamekeeper said to the actress.
MRS BENNET: Why, my dear, Netherfield is taken by a young man with an unfeasibly large penis from the north of England.
MR BENNET: What is his name?
MR BENNET: Bingley.
MR BENNET: Is he from Bradford by any chance?