The following is a clip from an episode from their first season called KAOS in Control. Maxwell Smart and Agent 99 are trying to interrogate a suspected KAOS agent. In this scene, Max is the only one who doesn't understand the difference between 'who' and 'whom'.
So you see, the joke is on Max because even when they explain how to use 'whom' he immediately misuses it.
MAXWELL SMARTOK 99, I think we can start with the interrogation now.99Check 86!MAXWELL SMARTOK Ratchett, start talking!99Who pays you?MAXWELL SMARTWho do you report to?99(whispers) Whom.MAXWELL SMARTWhom?RATCHETTLook, I'll tell you everything!MAXWELL SMARTJust a minute Ratchett. (To 99) Are you sure it's whom, 99?99Yeah, I think so because, um, whom is the objective, you see, in view of a preposition.RATCHETT(impatient) I would *like* to *make* a *statement*.MAXWELL SMART(Facing one direction) Who do you report to? (Facing the other direction) Whom do you report to?RATCHETT(Exasperated) It's *whom*.MAXWELL SMARTIt is? Oh! Well, then in that case maybe you can tell me, *whom* had access to the retrogressor!
I thought about how hard it must be nowadays to make jokes about the nuances of the English language. There was only one way to resolve this: Search Result Battle!
A search for "Who do you report to"So it doesn't look good for 'whom'. Popular opinion sides with Maxwell Smart. Sheepishly I must admit I would have agreed with him too.
yields 10,200 results.
A search for "Whom do you report to"
yields 872 results.
If you're interested in the clip, I've attached it below. The particular scene starts at about 0:43.
Update (June 23): My friend Maria summarized the whole article in five words: "Grammar jokes are not in."