What should i do for my birthday at 6 months pregnant and turning 25 years old?

I am turning 25 this weekend and i am 26 weeks pregnant. i also have a twin sister but she isn't pregnant. she is having a slip and slide party with a keg and since i cant do either of them i want to do something that is fun so she doesn't get all the fun. i don't really know what to do. i can go to the beach and lay out and get some sun with some friends but i am not sure how much fun this will be being 6 months pregnant. does anyone have any ideas?