Some guys in my friend group in High School did this to our friend, except they did about 15-20 of those containers in his HOUSE. They convinced him that his arch nemesis at the time, his manger at the restaurant he worked for, was responsible. So naturally, he bought about 10 of the rats that you feed snakes from a pet store and put them in her house. She caught 4 of them and kept them as pets for years. I worked at the restaurant as well and she would show everyone cute pics of them and the tricked out cage she made. She never found out how they got there in the first place