John Isner, naked, on a shirt

John Isner's grandfather has shirt of him from ESPN's Body Issue on it.

They say that grandparents will do anything to show how proud they are of their grandchildren. This would be Exhibit A.

Tennis player John Isner posed for ESPN’s The Magazine’s Body Issue without much fanfare (unlike a certain other person we know) until his grandfather decided to rock this shirt:

Now that’s taking pride in your grandkids. Funny thing, Isner’s tennis.com bio lists his nickname as “Grandpa.” We may now know why.