I managed a weak smile. Then I looked down at the alleged dog and had an instant flash fantasy of picking the little snot up, drop kicking him over the oak trees, throwing up my arms yelling "touchdown", and dancing around the lady as she screamed in horror.
Then I really grinned.
She, of course, thought I was smiling at her precious pooch and instructed her dog to "say bye-bye to the nice man". The lady resumed her power walk while the dog lagged behind long enough to deposit a little bomb on the trail.
Made me think that I should act on my fantasies more often.