"Santa at KBC again" joke

Santa is appearing on "Kaun Banega Crorepati (KBC)" with Amitabh Bachchan.
Amitabh: "Santa, you're up to Rs Fifty lakhs, with one lifeline left: phone a friend. If you get it right, the next question is worth a crore rupees If you get it wrong, you drop back to Rs 3,20,000. Are you ready?"
Santa: "Yes."
Amitabh: "Which of the following birds does not build it's own nest? Is it
A) robin, B) sparrow, C) cuckoo, or D) thrush."
Santa: "I'd like to phone a friend. I'd like to call Banta."
Banta answers the phone: "Hello?"
Amitabh: "Hello Banta ji, it's Amitabh Bachchan from KBC. I have your friend Santa here who needs your help to answer the final question. The next voice you hear will be Santa's..."
Santa: "Banta, which of the following birds does not build it's own nest?
Is it A) robin, B) sparrow, C) cuckoo, or D) thrush."
Banta: "Oh geez, Santa. That's simple. It's a cuckoo."
Santa: "Are you sure?"
Banta: "I'm sure."
Amitabh: "Santa, you heard Banta. Do you keep the fifty lakhs or play for one crore?"
Santa: "I want to play; I'll go with C) cuckoo".
Amitabh:" Is that your final answer?"
Pam: "Yes." Amitabh: "Confident?"
Santa: "Yes; I think Banta's pretty smart."
Amitabh: "You said C) cuckoo... And you're right! Congratulations, you have just won ONE CRORE!"
To celebrate, Santa flies Banta to Ludhiana. That night they go out on the town. As they're sipping champagne, Santa looks at Banta and asks him, "Tell me, how did you know that it was the cuckoo that does not build its own nest?"
"It was easy," replies Banta. "Everybody knows that cuckoos live in clocks."