Every Confidential that involves James Corden. That's right, BOTH of them!
"Open All Hours", the one for Closing Time, has Matt randomly deciding to go for an Almost Kiss, and apparently filming until 4 am makes the actors all loopy, because Matt, talking in character, films James, while warning him about miniaturized Daleks in the house. And then goes and uses the toy Dalek to knock over other toys and then attacks his face while they sing the theme song.
In that same episode, Matt holding a baby and singing the Itsy-Bitsy Spider to it, then suddenly stopping to stare accusingly at the camera.
And toss in some Adorkable because Matt doesn't seem to know the words to the song- "The itsy weensy spider, climbing up the wall where dee doo de doo".
Whenever Karen, Arthur & Matt talk to each other. Admit it, it's true.