I am going to be the party pooper, but having that many carbs all of a sudden could make you spend your birthday with sever stomach aches and bathroom problems. That doesn't sound like a reward to me.

Instead why not make most of the day even lower LC then you would normally have with plenty of veggies and protiens. Then at dinner have a treat, but see where you can lower the carbs slightly. Maybe make yourself an LC cake. There are tonsof LC cheesecakes and carb sense minicarb has a chocoalte cake mix that is amazing. It also has no sugar alcohols. Top it with a cream cheese cocoa frosting and you'd never know it was low carb.

Also stick to a serving and not gorge just because you are giving yourself permission to have a treat.