Can't believe all of the ideas coming in, thanks so much everyone!
PinkPony - That's another good idea, I could see some leopard print and neon pink being pretty cute together, lol though maybe not for my gelding. I'm tempted to combine all of these ideas and put them all to use...(then maybe everyone would think I was crazy and that would scare them off? haha)
PetitePyro - That is true, they'd have to be pretty dedicated to go through all that trouble and I have a feeling I know who stole this last bucket and I'm pretty sure the whole reason they did was out of laziness. And thanks for the input about the spray paint, I was worried that would be the case.
Palomine - Yes, I board and have to supply water buckets only. Which I don't mind supplying those, what does bother me is that we're down to only one non broken pick/maure fork for 30 some horses, which the BO is supposed to provide but it's such a pain I'm probably going to buy my own. People break them constantly and never replace them, but those at least I'll be able to bring home with me every time unlike the buckets lol. And painting or marking under the lip of the bucket was something I was thinking about doing, too. People may not notice it, but then at least I would be able to find them.