这是两则英文双关语的笑话
1 A linguistics professor was lecturing to his class one day."In English," he said,"a double negative forms a positive.In some languages though,such as Russian,a double negative is still a negative.However," he pointed out,"there is no language wherein a double positive can form a negative."
A voice from the back of the room piped up "Yeah,right."
2 A couple of clams were eating chocolate bars while two fish watched.
"Did you see that?" one fish said,as the clams finished their treat.
"They didn't offer us a single bite!"
"What do you expect?" asked the other fish."They're two shellfish."