Why is the number 3 funnier than the number 2 or the number 4?
In comedy, things often happen in threes (there is some aphorism about that, isn't there?).
Or, reactions are funnier in three beats.
And repetition is funny. The first time a gag appears, it may provoke a smile or just a notice- but the second time is funnier, the third funnier still- and soon the audience is expecting the next gag- and then if you pull a twist on it- you can bring the house down.