What people text, short for Oh. Kind of useless.
Josh: "Did you know that cars honk in the key of F?"
James: "O"
Josh: "Ohhh, wow. You couldn't have just typed "Oh". You saved a millisecond of your time. You purposefully decided to skip a letter of a word. Well, congrats. You really saved 4 milliseconds of your completely worthless mortal life.
James: "What the fuck"