A compilation of ideas from the wonderful community of reddit.
  1. Occasionally misspell words in sentences.
  2. Hold the door for someone when he is an awkwardly long distance away.
  3. When talking with them, stop them mid sentence and ask "...Have you been crying?"
  4. Rotate their tv/computer screen a bit to the left every time you visit.
  5. Reply "nice to see you again" when you meet them for the first time.
  6. Look over their shoulder when they enter their phone passcode, then, within earshot, work their passcode into a phone conversation.
  7. Every so often, replace "m" with "rn".
  8. When ordering fast food and they ask for a name, give the name of the person asking, regardless of gender.
  9. Use "bing" as a verb instead of "Google".
  10. If having a cigarette and someone asks to bum one, reply "sorry, I don't smoke".
  11. Look at someone's ear instead of into their eyes.
  12. Say "no pun intended" after a normal statement in conversation.
  13. Reply "I don't get it?" and ask for elaboration to a sexist/racist/gossipy statement.
  14. Ask someone "have you ever had that creepy déjà vu feeling?" then ask them the same thing a week later.