Edit: Following was the PM: Since it expcilitly allowed me to post the decision i went for the full quote.
I can think of two ways to interpret your bet. First, that bitcoin is at or above $500 on december 31 2015. Second, that bitcoin hits $500 at any point before that. I don't care which it is, you can choose. Please post your decision in the thread.
I will choose option 1. At that date a tranfser will be initiated.
I will gladly perfom a transfer to a owned address with a message of your choise (please nothing illegal!) to prove i am in possesion of a bitcoin. I would like some kind of proof that is its reasonable to assume you can uphold your end of the bargain as well. Can be per PM.
Edit: Added above edit notice.