If you are wondering on what event/promotion related to this bonus, usually there is information in the email you get but in other case Stake may give random bonus for those who are actively playing in specific type of gambling games.

It's a nice offer to take advantage of. It's just looking for a wager requirement, and I think that amount is very easy. Thank you, Stake.com. I will be waiting for my wins on sports, and maybe I can use that to wager more in casino games or slot games.