Помогите перевести, не с переводчика только!

1.
— You're so mature and polite for your age...
— Thanks, it's the stress.

2.
— What's the capital of USA?
— It's...U.
это вроде шутка, но до меня не доходит ее смысл.хд

3.
— My mom made me drink milk every day to get tall.
— You got tall horizontally. Horizontall.

4.
— What did you like the most today?