This project lets you draw with another person using online multiplayer! You should be kicked from the game if you are inactive for more than 15 seconds. Only two people can draw together. The screen is cleared every 45 seconds. The multiplayer isn't perfect, so if it says that you'll just have to watch and the pencils don't move, just restart the project and you should be able to connect.
New Scratchers can't use the multiplayer, try the single-player version here: https://scratch.mit.edu/projects/94708461/ I'm not sure if this works properly so if you find a bug/glitch, please tell me in the comments. :) Also, when you join with another player, you won't be able to see what they've already drawn before you joined (at least, I don't think you will. I haven't been able to test the multiplayer).