Because all their best runners, jumpers, and swimmers are already in the U.S.
... this joke was much more funny 30 years ago. Now it doesn't even work because to cross the border these days you don't need to run, jump, or swim. Just have a pulse and you'll get in... plus free room and board.
As I was wandering around, the clerk stopped me and offered to help me. I imagine I didn't look like his normal clientele, so I asked, "Do you have a copy of Donald Trump's book on his U.S. Immigration Policy regarding Muslims and illegal Mexicans?"
The clerk angrily replied, "Fuck off! Get out and stay out!"
I said, "Yes! That's the one. Do you have it in paperback?"
I accidentally joined a pro-secession organization. When I tried to leave, I was elected as their chairman.
#2.
A grasshopper walks into a bar. The bartender walks over and says “We’ve got a drink named after you!” The grasshopper replies, "You've got a drink named Eugene?
#3.
The repairs on Big Ben are expected to take 3 years. Which is quite a long time considering they're working around the clock.
"We're supposed to find the height of this flagpole," said Tyrone, "but we don't have a ladder."
The White guy took a wrench from his work bucket, loosened a couple of bolts and layed the pole down on the ground. Then he took a tape measure from his bucket, took a measurement and announced, "Twenty one feet, six inches," and walked away.
One nigger shook his head and laughed, "Typical honky! We ask for the height and he gives us the length!"