Mack is talking to his friend Don.
M: Hi, Don! How are you doing in your English class?
D: Not so well, I'm afraid.
M: What's the problem?
D: I'm not improving. Tell me, how come your English is so good?
M: Well, uh…I have an American girlfriend.
D: Aha! That's it. Now I know what to do. (He runs off.)
M: Hey, Come back! I was just kidding!

funny farm 疯人院   正式：mental asylum
improve sth = make a lot of improvement in sth
talk to(with) sb about sth  vi.       talk sb into doing   vt.说服
When he gave a speech, we realized that he was just talking nonsense.
He is a problem studnet.
greeting 招呼语
How are you doing in ...?   or:  How are you getting along?  近来怎么样？
久违的老朋友还可以说：How are you?  or  How have you been?
Howdy  美国南部招呼语  answer: Howdy
blind date 相亲,盲目约会
I am afraid (that省略) it is going to rain, so we can't go on a picnic.  我认为...(弱语气)
What's the problem (with)? = What's wrong? = What's the matter (with)?
goof around  浪费时间，混时间
Aha, that's it. = Aha, I get it. = I understand.
kidding = joking