He did what?

Wednesday, I text Son and asked him what he was doing.  He text back and stated, "Climbing trees with Gpa."

My reaction was What in the world is my father doing in the trees?

Then son text me again and it said "Squirrels nest."

I text back, "Send me a pic."  Well, unfortunately the picture will not post.  But it is of my dad up in a tree.  Good grief!