A person saying they have your back means they are there to help you out, they will watch out and take care of the things you're likely to miss, that they are a second set of eyes and hands for you.
This is the perfect description of Percy. I am sure that I can speak on behalf of my former co-workers and the rest of all our friends . He is not just a great friend, he is also an amazing father and a good husband. If I am not mistaken, he has been married for at least 25 years - and yes, to the same woman. So on this special day, I wish you a day that is as special in every ways as you are. May every moment of life be as wonderful and lasting as our friendship. Now let me take you back to some of the good times with some of our great friends.
Happy birthday to my BFF, aka Brother, favorite X-coworker, X-travelling buddy,
X-designated driver, Spanish coach, etc.
As the saying goes, "you will always be my friend, you know too much".