These keys come from www.fkn0wned.com and they hacked the database and your steam account will be banned if you buy these games.
http://www.reddit.com/r/Steam/comments/may0g/what_is_it_with_dead_island_and_portal_2/...
well i gave my key to a friend but it is my invite he said hed send it to whoever but im only looking to trade with trusted members anyway and i will go first so it dosent matter