This joke might be an old one, but it is still funny. Enjoy
Knott: Who's calling?
Watt: Watt.
Knott: What is your name, please?
Watt: Watt's my name.
Knott: That's what I asked you. What's you name?
Watt: That's what I told you. Watt's my name.
A long pause, and then from Watt,
Watt: Is this James Brown?
Knott: No, this is Knott.
Watt: Please tell me you name.
Knott: Will Knott.
Watt: Why not?
Knott: Huh? What do you mean why not?
Watt: Yeah! Why won' you tell me your name?
Knott: But I told you my name!
Watt: Didn't you say you will not?
Knott: Not not, Knott, Will Knott!
Watt: That's what I mean.
Knott: So you know my name.
Watt: Of course not!
Knott: Good. So now, what is yours?
Watt: Watt. Yours?
Knott: Your name!
Watt: Watt's my name.
Knott: How the hell do I know? I am asking you!
Watt: Look. I have been very patient and I have told you my name and you have not even told me yours.
Knott: You have been patient, what about me? I have told you my name so many times and it is you who have not told me yours.
Watt: Of course not!
Knott: See, you even know my name!
Watt: Of course not!
Knott: Then why do you keep saying of course Knott?
Watt: Because I don't.
Pause
Knott: What is your name?
Watt: See, you know my name!
Knott: Of course not!
Watt: Then why do you keep asking. Watt is your name?
Knott: To find out your name!
Watt: But you already know it!
Knott: What?
Watt: See, and you know mine!
Knott: Of course not!
Watt: Exactly!
Knott: Listen, listen, wait; If I asked you what you name is, what will be you answer?
Watt: Watt's my name.
Knott: No, no, give me only one word.
Watt: Watt
Knott: You name!
Watt: Right!
Pause before it hits him
Knott: Oh, Wright!
Watt: Yeah!
Knott: So why you didn't you say it before?
Watt: I told you so many times!
Knott: You never said Wright before.
Watt: Of course I did.
Knott: Ok I won't argue any more. Do you know my name?
Watt: I do not.
Knott: Well, there you go, now we know each other's name.
Watt: I do not!
Knott: Good!
Pause before it hits him
Watt: Oh, Guud!
Knott: Good.
Watt: No wonder, it took me so long, is that Dutch?
Knott: No, it's Knott.
Watt: Oh, ok. At least the names are clear now Guud.
Knot: Yes Wright.