Bob has had a few such scenes where they make an extended scene of him getting hurt and seeing how long they can keep the joke going before it stops being funny.
...And then they keep on doing it until it becomes funny again.
I remember the cast telling that the first such scene, where he repeatedly steps on rakes and the "camera" zooms back to reveal that he is standing on a field of rakes and no matter where he puts his foot he steps on another one, was a result of them needing to make the episode a few seconds longer. In fact, this change was done after they recorded the voices and they simply used the same "ouch" from Kelsey Grammer for each of the hits. Grammer himself was surprised when he saw the episode as he didn't know about the change.
