When Scooby and Shaggy get out of the Mystery Limo, they are sharing a milkshake. What fast-food restaurant did they get it from?

What flavor is the milkshake?

"You can tell what he's been reading lately."

"It makes you sneeze, which cleans out your nose."

"Dust is creepy, so it takes part in our mystery solving."

"You can see which books he hasn't read."