Originally Posted by
ian cruise
I'd dispute it's American humour, it's very much a trope established by British comedy such as Monty Python and carried on through programmes such as The Fast Show.
The humour is in the repetition and the recognition that the punchline is coming is what appeals to some, it creates a feeling of being "in in the joke".
Some American shows such as Family Guy have used this to great effect, though arguably the reliance on the repetition of punchlines has over time become the reason it has been deemed to have dropped in quality.
As to whether Haymaker's excited response is humorous or humourless, that's up to the individual. Personally, I'm a fan.