It's the Boxer dog way of saying hurry up, we need a walk. Especially if one has a full bladder! It's a soft wrestle, usually near or on someone's foot, quietly done, with just a few groans. It's part of our domestic life.
In this action shot, the big big dog has the little big dog's foot in his mouth! As mentioned in a previous post, Boxer dogs use a very soft mouth for this activity, and it is never bad-tempered.
I'm not sure but I think it beats the other - what we laughingly call Boxer p**n. When the big big dog has had a lovely walk and eaten his dinner, this is his next favourite thing to do. He lies on his back and wiggles, giving himself a lovely scratch all over. When he's done, he rolls over, hhmmphs and falls asleep. Bliss!