The 'r' Machine

Bert (fixing the machine): "Ha! Well, this machine knows what letter comes next. I put this here..."
Ernie: "Hi there, Bert. What's that machine you're working on?"
Bert: "Oh hi, Ernie. This is my latest invention, my automatic "R" detector."
Ernie: "No kidding."
Bert: "Yeah. Anytime this machine hears an "R" or an "R" word, it rings a bell. I'll start it up for you now...."
(sound of machine starting)
Ernie: "Wow! Look at that machine go."
Bert: "Now if you'll just say something that begins with "R"..." (bell rings)
Ernie: "What was that?"
Bert: "Oh, I just said "R". (bell rings) And when you say "R" (bell rings), the bell rings." (bell rings)
Ernie: "Hey! You said "rings" (bell rings) which begins with "R"." (bell rings)
Bert: "Right." (bell rings)
Ernie: "Why, that's remarkable! (bell rings) Hey! (Ernie laughs) Keeheehee! That's fun. Let me tell it an "R" riddle." (bell rings twice)
Bert: "O.K. Just don't go too fast. I don't know what'll happen if the machine gets going too fast."
Ernie: "O.K. Listen to this, machine: Roscoe really raised rabbits while Ruth rode the red reindeer. If Roscoe's rabbits raised a racket, why did Ruth's reindeer run the rabbits ragged?"
(bell rings 17 times)
Bert: "Hey, hey! Don't talk so fast. The machine is beginning to smoke."
Ernie: "Well, I only have one last poem here."
Bert: "Yeah, yeah, but listen.."
Ernie: "Robert rolled reddish radishes around the ring of rubber rubbish..." (The bell rings seven times and the machine makes a "Moooooooo!" sound)
(The machine explodes and makes a whistling sound)
Bert: "Hey, hey, wait! Hold it!....Wait!....Now look what you did!"
Ernie: "Oh my! The machine looks ruined."
(The bell rings and the machine makes another whistling sound)
Bert: "Rats!"
(The machine pops out a spring)