What about their Christmas-New Year art contest? It was a bit more than one month long, and there were only 33 art works declared. Some users even managed to present several art works. 10 winners. The chances to take last place and get 300 bucks was around 33.3%. By looking at the works, if a participant put just a little effort and don't participate just to participate, his chances to win were rather high.
Especially such giveaways where the user also has to do something for it (for example, make a drawing) are quite lucrative, since there are usually hardly any participants. "Standard giveaways" where you just have to enter your username or register with an email address are completely overrun, because of that winning is almost impossible, even if there are eg. 10 winners in total.