Most Helpful Guy
buy a small cake and one candle and take it in your room light the candle, put it on the cake and celebrate your birthday1
Most Helpful Girl
Is there a city event going on that weekend? Like a market or fair? I like to go exploring that, or a new part of town. Then you can treat yourself to a nice lunch or dinner, maybe get a small cake or ice cream, or anything you want. Maybe come home and watch your favorite movie or find one you haven't seen that you've always wanted to watch.
I've actually done that on my birthday a few times. I didn't want a party or get together that year.1