You can join this giveaway by typing in the keyword that is set by Tim.
MSSbHot posts a chatline every couple of minutes with the word that you need to type in chat.
Not sure if you already typed the keyword? Type !mellows to check. If there is a (k) after the amount of Mellows you have? You're in! If not, type the keyword.
These giveaways are free, so you don't need any Mellows to join.
You do, however, need to be a follower on Twitch and Twitter!