Birthday Wishes to Brother or Sister

I love how age doesn't change our relationship.
We may as well age together, we've done just about every other unhealthy thing together.
Isn't it great when you and your own best friend get to have the same parents?
If you ever feel too smart in your older age, just come hang out with me. I can always tell you how much smarter I am than you.
Siblings and birthdays are two things you will never get rid of or change. We both like to remind you at least once a year how old you are getting.
I'm still not sure that you and I were really born as siblings. We're nothing like each other.
Siblings have rivalries, but I like to think of it as older and younger sibling competition. You win the age competition every time.
Celebrating your birthday is just like celebrating the birthday of a friend I didn't get to choose.
You are my favorite brother/sister born today!
Thanks for all the fun times growing up. I would not be the same person today, if it weren't for you.
I've been able to enjoy having a great brother/sister for __ years now!
Siblings are good at keeping secrets, like who broke the lamp. So your real age is safe with me.
I know we didn't always get along growing up. When I look back over all the years and birthdays, I realize how lucky I am to have you as a sibling. We have had a lot of fun.
I love having you as a brother/sister, and I love that you are always going to be older than me. Have a great birthday.
I am glad I was able to be your little brother/sister, because I was able to learn from all of your mistakes. I am glad you were born before me.
No matter how old we get, you’ll always be my big brother/sister. I love you.
I probably hate you having birthdays and getting older just as much as you do. When you get older I know that I am getting older too since I am your brother/sister.
Did I ever tell you how glad I am that you were born __ years ago? I am especially glad that I had someone to be an ally against mom and dad’s rules.
I still look up to you after all these years of you being my big brother/sister. I hope you have a wonderful birthday.
I remember how when we were kids we couldn’t wait until our birthday. We would count down the days. Now we dread birthdays and try to deny that they even happen.
I think there is a connection that brothers/sisters have with each other. Because of that, I feel like I got a little older on your birthday. Darn you for that!
I have been blessed in my life to have a brother/sister like you. We have gotten closer through the years even though we don’t see each other as much as when we were growing up together. I appreciate our relationship and the blessing it has been in my life.
I am glad that you were born into our crazy family, although I think you were the wildest one of us. Thanks for making things fun growing up. Have a wild and crazy birthday!
Remember when we were able to eat all the cake we wanted and we wouldn’t get fat? I guess somewhere along the way our birthdays have caught up with us. We are just boring old people now. I am glad we are in this together.
Remember how you used to try to help me blow out my candles? Now you need help blowing out your candles, because there are so many!
Between me picking on you and you telling on me, we were able to keep mom and dad pretty busy. I think that is our biggest accomplishment from growing up. I couldn't have done it without you. I am glad you were born.
I guess now is a good time to tell you that mom and dad adopted you, and we don’t actually know when your birthday was.  Happy made up birthday!
No matter how old you try to get, you'll always be younger than me. Nice try. You still have to listen to me.