I have a house near a beach. Visiting children usually want to bring pebbles back from the beach, which I'm not terribly keen on. Technically it's illegal to take things from the beach but, more practically, I often end up with buckets of pebbles at the end of the summer as the children lose interest once they've bought the pebbles back.
WIBU to say that any pebbles have to go right in the parents' car once we get back and are not to come into my house? I find that the parents are a bit keener to enforce the whole "leaving everything at the beach for others to enjoy" when I say this but all the same perhaps it isn't very welcoming.