I suspect I am. And what seem like a good idea after 2 glasses of wine, does not always seem so good in the cold light of the morning.
Basically, hundreds of high school leavers (aged 17/18) gather on a local beach, every year on the 16th of May. They drink insane amounts of alcohol, and they leave so much rubbish and bottles and cans (and sick) behind, that I would not dream of taking the kids to the beach for at least a week after...
Dh is called out on red cross duty, to man a tent and take care of these "kids". Then they shout and scream as they walk passed the local residents as they walk into the city to continue the party in clubs and pubs...
I wonder what the reaction would be if they came to the beach and found hip bones and a spine, and large other bones?
My son found a complete reindeer skeleton, which he insisted on picking up and carry home (in a bin-liner). It is massive. The bones were squeeky clean, and found baking in the sun,in some remote area. The animal had no doubt died from either starvation or hypothermia, so natural causes.
Without the skull, and all four legs, for the non-medically trained, the bones could be anything.... I was amazed how similar the hips were to human hips, from a non-professional perspective of somebody who very rarely peruse bones.
So Aibu to attempt to put a dampener on their party? 
I expect I am. It could traumatize them.
However, it is not illegal to drop bones on beaches?
It is not really a good joke, is it? It is rather tasteless?
And I suspect my son would be devastated if I were to help my self to his budding bone collection...... 
ah well, as you were.