For me, my favourite big moments include:
* "Don't tell them Pike!" scene from Dad's Army (classic).
* Paul Merton's News of the World T-shirt on Have I Got News For You.
* "They say of the Acropolis, where the Parthenon is..." from QI (I laugh every time I see that clip).
* The Mastermind sketch from The Two Ronnies.
* The scene in the Porridge episode "No Peace of the Wicked" where Feltcher prays to God for solitude and then the chaplin arrives.
* "Nobody expects the Spanish Inquisition!"
* Jez eating the dog in Peep Show ("'Mummy' is probably the turkey's nickname. It could easily be.")
* The anxious Nazis ("Are we the baddies?")