apart from all the times it actually is free
even then thats genorocity, and then you are paying some one kindness by accepting it
that being said, OP, when was the last time a complete stranger offered you something free? with the emphasis that it would cost you nothing and that it was a painless little process, did you just walk past them? because that would be the best answer. especially on the internet.
EDIT: if your cousin doesn't even know himself then don't do it man... or woman... its not like your day will be ruined if you just pass it up. you lost nothing, but if you click it or whatever you might loose something like your identity or your computer (via virus)