Old?

Tonight in true Thanksgiving/Christmas fashion we set up our tree. No decorations (the girls were in bed). Just the lights and angel. Before bed Derek, Raymond and I were laying on the floor admiring the lights. Raymond was talking about random things, as usual. He knows when events are going to happen based on other events. Christmas is after Thanksgiving. His sister will be born after Christmas. He asked what was after his sister. I told him Jakobe and moms birthdays. He asked Derek when his birthday was. Derek said in a couple of weeks. Raymond said "o how old will you be?" Derek answered 28. Raymond, shocked, says "thats really old". I could not stop laughing. Is it really that old?