Space Quest has loads of amazing quotes:
"You get the ladder and put it in your pocket. Ouch." (Narrator, aboard junk freighter)
"Don't touch that. We don't know where you've been."
"This rough area tastes strangely like blood. Oh, that is blood! You shredded your tongue! Your mother should have warned you about licking strange areas."
"It's a button with a strange symbol on it. Perhaps it means 'self-destruct', or maybe 'change return.'"
"You lick a thick smear of filth off the street, finding the taste unpleasant. You quickly swallow it. What a smart person you are."
"Not far below you is a large horizontal plane which proves beneficial in maximizing the exploitation of gravity."
"My, this is one hot planet! But you don't care; you're protected with Thermoweave Underwear!"
"Why don't you just say, 'Hey, mister. I've always wanted to catch a really good look at the inside of my colon. Perhaps you can help me.'"
--
Also, Sam & Max:
Max: I'll name him John, since that's where we found him.
Sam: Look Lactose, we'd rather you didn't eradicate the whole human race.
Max: Some of our closest friends claim to be human.
Sam: I've got something in my eye.
Max: Try digging it out with a fork. That always works for me.
Sam (at a wishing well): I wish I knew what Max was thinking.
Max (in his mind): ..............
Sam: Well, that was a waste of money