Whenever someone asks me to take a picture of them, I always take two photos. I tell them the second one is to make sure it's good, but the truth is the first one was just a picture of me while I pointed their phone at them.

I imagine when they look back they ask "Who is this guy? OH! He's the one who took the picture of us!" and then they probably delete me, but just for a few seconds, I lived rent free in their heads.