A buddy of mine used to help write, shoot, and produce a cable access show back in the early 90’s. Occasionally I’d stop by and watch them film it. VERY low budget - but they did make me laugh.
This was one of my favorites: http://www.youtube.com/watch?feature=player_detailpage&v=z2WHTN57XIY
Someone on the set can’t help himself during the fight and you can hear him chuckle.