Naked guy near Walkers place

Today morning around 10 AM, me and my wife were sitting in the living room, having a casual discussion over a late breakfast that from nowhere a fully naked young man appeared in our backyard window. We were shocked and I jumped to the window to see what has happened. I saw a guy only wearing his socks running around our building speaking something, going to the end of the backyard, making some weird sounds at the end for few seconds and then running back the same way he initially came. All this within 20-30 sec. He had some pinkish stripe painted on the shoulder, I guess, and was bulky.

We had a laugh and thought, how we could have explained this to our kid, if she was not in school but were also concerned, if this is a mental health issue.

Any one has any clue on this?