That truck driver knew what he was doing. Truck drivers are jerks like that. They know that they can get away with anything. It's not like this is a little two door Honda that you can kick a dent into. If the truck wants to spray you with mud, it'll do it and then cruise away. If you try to chase it, it can just run you over. That's why we get such pleasure off of seeing big trucks crash. Unfortunately, that's not what this picture is about.
These two look like they are close enough to the beach to suffer a little bit of mud. Maybe they can catch a mud wave with that surfboard. This is just me looking on the bright side. This must have been horrible. That's not just mud and water. That's rocks, grease, oil, water, and maybe even urine.