But then here's one to add.

Hollanders (Dutchmen) and Belgians have a long tradition of jokes between them. The Dutch are about thriftiness, the Belgian about dumbness. As both categories exist worldwide this one might be known already:

An angry Belgian steps into the shop where he bought a chainsaw the other week.
" Fine saw you sold me last week " , he says furiously, "It took me all weekend to saw one single tree "
"Well" . the salesman says: "Lets have a look."
He starts the chainsaw on which the Belgian gives him a queer look and asks: "Hey! what's that sound? "