I played through the game with my cousins, and everything became a lot more funny that way. When we heard "LIKE A VOLCANO", we had to pause the game until we calmed down.
When I played through Sam & Max Season 1, this was the funniest dialogue for me:
Sam: Hey, Sybil. What's new in the world of frequent, random career reassessment?
Sybil: Hi, fellas. I'm really excited! I found the perfect job for me.
Sam: You don't say.
Sybil: That's right. I, Sybil Pandemik, am now a professional matchmaker.
Max: I thought I smelled phosphorous.
Sam: I thought I smelled that joke coming down the turnpike, burning oil and dragging its muffler.
Sybil: It's a dating service, Max. I figured that if a smart, successful career woman like me could be having so much trouble finding a date, there must be plenty of other people who could use help.
Sam: You're having trouble finding your soulmate?
Sybil: You don't know the half of it. It seems like all the guys I meet are total losers. No offense.
Sam: None taken. Hey!
Sybil: Or else they're borderline psychopaths. No offense.
Max: None taken. It's the borderline cases you have to watch out for!
I didn't hear the rest of the dialogue because I was laughing so much.