Since a person can only have one YorkieTalk account, you can ask a friend or admin or moderator to PM your Secret Buddy for you, and ask for their email address, as well as ask if their Secret Buddy can contact them secretly. If they agree, you will then have their email address.
Then, sign up for a free email account, at Gmail, Hotmail, Yahoo, etc., and email your Secret Buddy.
This is a very cute and ingenious idea, one that I don't think anyone has thought up before in a YT GE.
Please don't torment your Secret Buddy too bad!