"What credit card do you want to put that on?"
"Caash, prease."

Sheriff Truman's best moment...

Cooper: Harry, I think we’re saddling the horse before we’re ready to ride.

Truman: I don’t follow.

Cooper: I don’t think Ben Horne killed Laura Palmer.

Truman: What?

Cooper: You should release him.

Truman: Cooper, I’ve backed you every step of the way but I’ve had enough of the mumbo-jumbo. I’ve had enough of the dreams, the visions, the dwarfs, the giants, Tibet and the rest of the hocus-pocus. Now we’ve got hard evidence against Ben Horne and it’s my job to lock him up.

The over-explicitness of the catching fish-metaphor dialogue makes it funny. I can't remember all the metaphors but here are some samples...

Cooper starts it all when he goes fishing at One eyed Jack's: "I have a trout on the line. This one's a keeper." 

"Hold the line, we'll set the hook."

"Bla bla bla... as soon as the big fish shows it's fins."

There are more, I just can't remember them all...

Ed: I don't believe in fate. You make your bed. You sleep in it.

"What credit card do you want to put that on?"
"Caash, prease."

Good call, TheFalls.

The only part of the alternate pilot ending (outside of the Red Room) that I really like:

Make a wish.

What is the alternate pilot ending like? 'Cos it seems like it would be a bit tacked on if they suddenly revealed the killer.

And, what is Helvetica?
 

It's totally tacked on, you're correct. And the Red Room stuff gives a very different impression than it does in the series, in my view.

Helvetica is the secret weapon with which Booth and I killed the fake album covers thread.

"What credit card do you want to put that on?"
"Caash, prease."

"Harry, I'm going to let you in on a little secret. Every day, once a day, give yourself a present. Don't plan it, don't wait for it, just let it happen. Could be a new shirt at the men's store, a catnap in your office chair, or two cups of good, hot, black coffee. Like this."  -Dale Cooper

"What credit card do you want to put that on?"
"Caash, prease."

I've always loved the way Laura says "Uh-oh, here comes mom with milk and cookies" on Jacoby's tape.

Also, the way Leo shouts "YOU BROKE MY HEART!" when he's about to kill Shelly and torch the mill is so deliciously ridiculous. Eric DaRe was very good at balancing the menacing and the laughable parts of Leo.

"What credit card do you want to put that on?"
"Caash, prease."

"What credit card do you want to put that on?"
"Caash, prease."

Harry. Your alright.

and....

Coop! What happend to Josie? (I ask myself that question every other day)

Albert: 

"Agent Cooper, I am thrilled to pieces that the Dharma came to King Ho Ho Ho, I really am, but right now I’m trying hard to focus on the more immediate problems of our own century right here in Twin Peaks"

"Has anyone seen Bob on earth in the last few weeks?"

For me, Coop's answer is even better. "No, not yet."

Speaking of deliciously ridiculous: "He is BOB, eager for fun. He wears a smile, everybody run." Of all the actors in the known universe, Al Strobel is the only one who could actually inject these lines with some gravitas.

"What credit card do you want to put that on?"
"Caash, prease."

In the last episode when possesed Cooper squeeze out all the toothpaste I always think of Mike saying "He is Bob, eager for fun..."

This may not be a quote, but for me one of the funniest moments of season 1 is when Shelly turns off the TV after the narrator says "and each week brings a promise of an INVITATION TO LOVE." Shelly says "yeah, right," and it cuts to this absolutely ridiculous photo of Eric DaRe doing Leo Johnson's straight face. It just makes the house look gaudier and the scene look more like a soap opera, I love it. 

That is if emptying a perfectly good tube of toothpaste is your idea of a good time.

"What credit card do you want to put that on?"
"Caash, prease."