Whenever Jonathan gives a Summation at the end of the episode. Usually an introspective, sarcastic, rather anti-social guy, he always gets a gleam in his eye and speaks with relish whenever he's given the floor.
After being little more than a tagalong for the duration of Satan's Chimney, Carla saves Jonathan's life after they confront the killer. He is on the verge of strangling Jonathan, but Carla manages to talk him down after she spots a dog on the premises and tells him that Jonathan's (non-existent) Scottie will die of neglect without him, correctly intuiting that the killer is a dog-lover.
Halfway through The Black Canary, the murder victim's husband is revealed to be a crack-shot. This is slightly ominous considering he's infirm in practically every other respect, and that his wife shot herself. At the end of the episode, the wheelchair bound and half-deaf man shoots the rope that his daughter is trying to hang herself with from an upstairs window. "There's nothing wrong with my eyes," indeed.
The Three Gamblers - Jonathan disarms a psycho wielding a gun. With a playing card.
Jonathan has these in virtually every episode as he teases his various sidekicks about the solution to the current mystery. By far the best one comes in the episode "The Scented Room". His client is noted theatre critic Sylvester LeFley who wrote a damning article about a show Jonathan was involved in. In the episode he has a valuable painting stolen and Jonathan's CMoA comes with this line:
Jonathan: I know exactly how your painting disappeared, Mr. Le Fley. I'm just not gonna tell you.
Sidekick Maddy Magellan's CMoA comes in the episode "Ghosts Forge", when she pulls off a very impressive disappearing trick. Jonathan isn't fooled, of course; it's her triumph over the abominable Mimi Trantor that makes it so awesome.
When one of Adam's Girls Of The Week, a character who is given barely any lines and only on screen for about two seconds, tricks him into wearing a Japanese kimono with calligraphy down the front that reads: "I am full of shit." Adam happily wears it around the theatre until an unimpressed theatre critic tells him what it says.
Rik Mayalls Gideon Pryke is nothing but a walking, and later wheeled, Moment Of Awesome. As intelligent as Jonathan and Genre Savvy enough to keep ahead of everybody, in The Clue of the Savants Thumb he realises that two of his officers have been secretly working against him, foils their attempts to murder four people, then disables them both with nothing but his thumb.