The third definition of slapstick being 'ritualistic', or perhaps 'repetitive' might be a better term, is interesting. The 'rule of three' in slapstick comedy is nicely illustrated in Laurel and Hardy's 'Busy Bodies'. (https://www.youtube.com/watch?v=ZujoJaR2ERY) At about three minutes into the film there is the repeated gag of Oliver (and Stan) having a collision with a plank of wood. The first sets up the gag, the second develops it and just when you least expect it, the third twist of the gag provides the final conclusion. It's interesting that it is three times for the perfect slapstick routine. A fourth repetition would over do the joke making it boring and predictable. What do you think?