From the second live action movie, while Scooby and Shaggy are surrounded by costumes of previous monsters that have been brought to life.
Shaggy: We have to remain calm.
Scooby: (screams in fear)
Shaggy: CALM, Scooby Doo! You're not being CALM!
Scooby: (slaps him)
Shaggy: I needed that!
Scooby: (slaps him again)
Shaggy: I needed that, too!
Scooby: (punches him)
Shaggy: You're pushing your luck, Scoob!