Daphne, Velma and others in “Unfinished Business”

Daphne

Look at that! Are Manticores double-jointed?

Velma

This is no Manticore, Daphne. This is... (unmasks the Manticore)

Hot Dog Water?

Velma

Just as I suspected. It totally makes sense when you put the clues together. Someone with computer skills had to make that fake website, and Hot Dog Water has those skills. And remember, just before the Manticore attacked, I smelled something familiar. It was briny, greasy hot dog water. (to Hot Dog Water) But what I don't know is why Shaggy and Scooby had such high voices after you attacked them before, or why you'd want this amusement park to close so badly.

How could you know? Your intellect is so far inferior to mine. (takes off the Manticore's outfit) It all started on a boring Friday night when I didn't have a date.

Velma

Hard to imagine.

I decided to run some experiments on the steel used to build the park's rides. I found that if you melted the steel down and combined it with chromium, stalagmite, and mercury phosphate, it created a kind of super helium. Shaggy and Scooby must have inhaled some helium gas from the Manticore's posterior relief hole. That's why their voices were so high. I figured if I could get the park to close, I could take all the steel, melt it down, and sell the super helium to the Australian zeppelin fleet. I'd have made a fortune and shown you up in the process, Velma.

Daphne

Another mystery solved.

It still seems like something's missing.

(reads) "Meddling kids and their dog will foil your plan".

Yep. That would be it.