Here's a dumb blonde joke I once read in
Reader's Digest, that was based on a true story that involved gangsters...
There once was a ventriloquist, who took to the stage, with his little dummy sitting on his knee, and proceeds to go into a series of dumb blonde jokes; everyone in the audience gets a kick out of it, save for one platinum beauty in the front row, who stands out of her seat, "How dare you!" She said, "that stereotype is very outdated, not all blondes out there as that dumb you know!" At this point, the ventriloquist feels a little bad about the routine and begins to offer an apology to her, but she responds with "You keep outta this, I'm talking to that little jerk sitting on your knee!"
Interestingly, the true story that was based on involved a ventriloquist, who had his dummy raz a group of gangsters that were sitting in his audience; in a fit of peak, one of the gangsters actually gets up on stage, and punches the dummy so hard its head pops off. The gangster actually stood over the dummy and threatened to kill it if it made anymore jokes like that.