Another idea: when Grifter asks you for your birthday, and you put that your birthday is the day that you are currently playing it, then maybe Grifter wishes you a happy birthday
Heh, i think that's a great idea. And it also seems to me that it would be worth adding Eric's canon date of birth there too (just like with his canon name at the beginning of the game - just don't write any date and press "enter").