found a good one on that dirtyjokepost:
While visiting England, George Bush is invited to tea with the Queen. He asks her what her leadership philosophy is. She says that it is to surround herself with intelligent people. He asks how she knows if they're intelligent.
"I do so by asking them the right questions," says the Queen. "Allow me to demonstrate."
She phones Tony Blair and says, "Mr. Prime Minister. Please answer this question: Your mother has a child, and your father has a child, and this child is not your brother or sister. Who is it?"
Tony Blair responds ,"It's me, ma'am."
"Correct. Thank you and good-bye, sir," says the Queen. She hangs up and says, "Did you get that, Mr. Bush?"
"Yes ma'am. Thanks a lot. I'll definitely be using that!"
Upon returning to Washington, he decides he'd better put the Chairman of the Senate Foreign Relations Committee to the test. He summons Jesse Helms to the White House and says, "Senator Helms, I wonder if you can answer a question for me."
"Why, of course, sir. What¹s on your mind?"
"Uhh, your mother has a child, and your father has a child, and this child is not your brother or your sister. Who is it?"
Helms hems and haws and finally asks, "Can I think about it and get back to you?"
Bush agrees, and Helms leaves. He immediately calls a meeting of other senior Republican senators, and they puzzle over the question for several hours, but nobody can come up with an answer. Finally, in desperation, Helms calls Colin Powell at the State Department and explains his problem.
"Now lookee here, son, your mother has a child, and your father has a child, and this child is not your brother or your sister. Who is it?"
Powell answers immediately, "It's me, of course, you dumb cracker."
Much relieved, Helms rushes back to the White House and exclaims, "I know the answer, sir! I know who it is! It's Colin Powell!"
And Bush replies in disgust, "Wrong, you dumb shit, it's Tony Blair!"
