My dog Jagger loves to do "fly bys", well thats what we call them anyways. We live on an acrage so sometimes it can get really muddy, he will wait until somebody unsuspectingly stands near mud or a dirty puddle and runs full tilt into it spraying mud all over the bystander. he will have a goofy smirk on his face when the person realizes they have been hit. that is the only time he runs past people, so he is intentionally doing it.