I know you guys are having some fun here, but that got me wondering.
I did a bit of research and the Abbott & Costello routine is from the movie "
Little Giant" which was put out in 1946. The Ma & Pa kettle one was done for "
Ma and Pa Kettle Back on the Farm" which was put out in 1951. So, for the purposes of these two bits, Abbott & Costello did it first.
However, we are talking about Vaudeville here and so it is very likely that it was a bit done by both for a long time before it ever made it into film and neither one were the first to come up with it.