Jonathan Creek/Funny

• This exchange, whilst Maddy is locked in a jail cell on suspicion of conspiracy:

Maddy: What if they give me some kind of truth serum?!
Jonathan: It wouldn't stand a chance.

• Adam's attempt to cash in on the success of Derren Brown, which ends with him being attacked by an angry mob of persons of small stature. (Amazingly, It Makes Sense in Context.)
• The episodes featuring Adam's attempts to play Follow the Leader with David Blaine are also strong candidates.
• When Adam's latest Girl of the Week (an Austrian seamstress) misinterepts his need for a "frog-coat" for a Jack-the-Ripper sketch and ends up making him a giant frog costume, complete with paper-mache head and flippers for his feet. Even better is Jonathan's reaction to it:

Jonathan: Is this it then, is it? Through the swirling fog of Victorian London a young girl is slashed to ribbons by Toad of Toad Hall!

• Come to think of it, pretty much every single episode where Adam has a prominent role in the subplot probably counts.
• This troper particularly remembers Maddy and Jonathan, mid-case, stopping to have an extended argument about the lyrics to the chorus of "My Friend the Witch Doctor". It almost qualifies as a Non Sequitur Scene considering it has absolutely nothing to do with anything they've been discussing in the episode up until that point, and is never mentioned again. It also serves to illustrate the fact that despite their sniping at each other, the two of them are most happiest when they're squabbling over nothing.

• Nigel Planer's cameo in The Reconstituted Corpse as Maddy's blind date. A stereotypical British gentleman, reminiscent of John Cleese, who briefly speaks of sex in a rather loquacious fashion.
• Almost any time Adrian Edmondson is on-screen as Carla's pompous, pretentious but strangely loveable husband Brendan.
• Maddy's flat is burgled and the lock on her door is taking a while to fix. In the meanwhile, she leaves a post-it note on the door to deter others: "Burglars, don't bother - I've been done." Jonathan remarks:

"Interesting security system."