Yves,
sadly we have to live with these a**holes. We leave ourselves open to it. As Marc said, we hold a stigma inside, that says, just blame it on the easy target.
I try to be easy going at work, but people so much take it as being, I am an easy target, they do things like hiding food, and security passes, it pissed me off one day, when I said to the supervisor, who was new to the job. I have lost my security keys "in the room"
After quizzing my colleagues, who all denied taking it, I said to my supervisor, she must alert security over the loss. I then addressed my colleagues again and said, do you really want to put this girl into all the trouble of filling out all the forms necessary to avoid security issues, I soon found the culprit.
They always hide things from me, sometimes my lunch, other things, they think it is some joke

Sometimes I turn the joke on them though
I know how hard it is to put up with this behaviour, I have seen it so much in my life.
I would guess, like me, you just want an easy life but find these a**holes, just try and ruin it for you, they don't see the fragility, they don't have any compassion.
Hey, though are you not like me?
I got blamed for everything when I was a kid, and took the punishment, because. I was always the "odd" one out, the runt of the litter!
Always I remember one thing, when I bred dogs, I said to the owner of the bitch, give me the runt of the litter, the dog the mother throws out of the basket, the dog she doesn't care for, I always got the best dog.
Maybe the ugliest dog to them, not to me. Always found a true friend in this type of dog, "hey you want me"? Nobody else does!!!
True friend for life, think about how we make friends?
take care
ste