There's these four Irishmen in a bar, all drinking Guinness. One of them 
is looking rather puzzled, so another turns to him and asks him what's the 
matter.

1st Irishman: Well, I was just trying to remember what 2 plus 2 is.
2nd Irishman: Oh, that's easy, it's 147.
1st Irishman: No no no, that can't be right. How about you, Fergus, do you
              know what 2 plus 2 is?
3rd Irishman: Hmmm ... could it be Wednesday, perhaps?
1st Irishman: No no no, that doesn't sound right either. How about you               
Pat, do you know?
4th Irishman: Simple, the answer is 4.
1st Irishman: Of course! How did you work it out?!
4th Irishman: Aha, that's where brains come in! I subtracted 147 from
              Wednesday!