A Czech refugee goes from door to door trying to find someone who will take him in and hide him from the communists. After knocking on doors all day he is despaired that not one home would take him in. He meets up with his brother and tells him of his woes.
His brother asks "Well, what is it that you say when you knock on a door and the homeowner comes to greet you?"
He says I always say the same thing but they just slam the door on me.
"But what is it that you say?" his brother reiterates.
"Excuse me sir (or mam) but can you cache a Czech?"