Drasnian Secret Language is a form of sign language used by Drasnian's to pass secret messages.
The secret language is employed using finger movements. A clever adept with can hold a verbal conversation on another subject while conversing in the Secret Language.
According to Silk; big, exaggerated movements are "shouting", which is a bad habit as it contradicts the language's secretive nature. It also doesn't help to "mumble": to use imprecise movements or start a new motion midway though a previous one.