In "What Happened at the Zoo", Bert comes in and sees a very bored Ernie.

B:  What happened today, Ernie?
E:  Nothing.
B:  I'm sorry to hear that...but wait, weren't you at the zoo today? 
    Things are always happening at the zoo.
E:  Not today, Bert. (looks at finger)  Well, there was one thing.  See, I 
    got this teeny, tiny scratch on my finger here.
B:  That's too bad.  How did that happen?
E:  I think it must have happened when I fell down.
B:  But how did you happen to fall down?
E:  I think it was when I was running away from the big dog.
B:  But why waas a big dog chasing you?
E:  Well, he wasn't, Bert.  You see, I _thought_ he was, but actually he 
    was running away from the tiger.
B:  The tiger?!  What was the tiger doing out of its cage?
E:  The monkey let it out.
B:  But what was the monkey doing out of its cage?
E:  Well, I think it got out when I opened the door of its cage to put the
    rabbit in.
B:  But why were you putting the rabbit in the monkey's cage?
E:  Well, with all the elephants running around, I was afraid it would get
    stepped on.
B:  Why were the elephants out of their cages?!
E:  The hippopotamuses were out, why not the elephants?
B:  But how did the hippopotamuses get out?
E:  Well, I didn't see it, Bert, but I think it was when the bus crashed
    into their cage.
B:  Why would a bus crash into the hippopotamus cage?
E:  The driver couldn't see because of the lights, Bert.
B:  What lights?!!
E:  From the flying saucer.
B:  Ernie, you said nothing happened at the zoo today!!!!
E:  Well, I thought so, Bert, but I was wrong.
B:  I'll say ou were wrong!!!!
E:  Yeah.  See, I got this teeny, tiny scratch on my finger here.