Ehh

• They tend to get the sign wrong, or straight up not know it and end every sentence with "or the other way around"
• their room is a mess
• they have a soldering iron and a box full of Arduinos/Rasberry Pis/ESPs
• they have weird hobbys, (or none, because their work is sufficiently shaped like weird hobbys/obsessions)
• they regularly say “local minimum” and “higher order effects”

What did I forget?