Currently StackOverflow is celebrating their 10 millionth question. They are randomly distributing a total of 400 t-shirts among participants, over a period of one month. Participation is done by either tweeting under a certain hashtag, or putting the corresponding hashtag on your SO user page.
I looked all over the announcement page and didn't see any mention of terms and conditions, and this got me wondering. As a non-US citizen, I'm used to seeing online contests from US-based companies excluding non-US participants from being eligible winners because of the various localized rulings on what constitutes a legal lottery.
Which legal issues should you be expecting, when organizing a giveaway like this one without terms and conditions?
