In what's almost par for the course for LucasArts adventure games, there's an item (actually two: Bernard's Flux Dynamics textbook and the disappearing ink) that you can use on almost any character and cause a variety of hilarious and unexpected reactions. Among the greatest ones are Oozo the clown (textbook) and the guard tentacle, when Laverne's been let out of jail to go to the bathroom (ink).
Tentacle Guard: Eww! In the grass! Do that in the grass! Lousy humans...
For Oozo, Bernard takes the book out and knocks the clown over without even realising it, prompting it to knock him back.
Oozo: Ha. Ha. Ha.
Bernard: Some people have no appreciation for the finer things in life.
Purple Tentacle: The only three-headed monkey here is in front of us.
Bernard: "Now what am I gonna do?"
Dr. Fred: "I think I made myself perfectly clear. Step One: Find Plans. Step Two: Save World. Step Three: Get Out Of My House! Now let's get cracking!"
Bernard puts a hamster in the deep freeze for Laverne to recover in the future. She revives the hamster in a microwave oven, while Breaking the Fourth Wall to tell us that kids who try this in real life are taken away.
When Hoagie has to push the kite, simply ignore Benjamin Franklin's signal and do nothing:
Benjamin Franklin: What part of the word "now" you don't understand?
(Hoagie then has three possible answers.)
The whole ordeal to steal the gold-plated pen from the Founding Fathers: First make George Washington lose his dentures with an Explosive Cigar and them replace them with a pair of chattering teeth, which will make John Hancock think that Washington is cold for which they will light a fire, then Hoagie uses Hancock's blanket to block the chimney which will cause smoke to fill the hall making the Founding Fathers think there's a fire and jump out of the window in panic.