its yggy: HAHAHAHA!! Oh PLEASE do that!!
Hehe or maybe if he wanted to be REALLY spiteful, he could just move the bench completely in front of her door so she trips over it in the morning.
She has to know that it bugs him because he keeps moving it whenever she moves it back. Either she's stupid, she's playing with him to see how long he goes before saying something to her or she's crazy. Come on. How could you not know? You obviously noticed something is different every time you come home; you mean to tell me it wouldn't occur to you that maybe the bench bothers him? Plus, for her to move it back 2 inches makes me think she probably is crazy.
Hmm he could also superglue the bench to the wall. Now THAT would be funny (oh to be the security guard watching that comedy of errors play itself out on the CCTV. LOL!). When she comes over to complain, he could act all innocent like "those damn kids must have done it!" I mean she put it outside in (presumably) public view, it's not unreasonable to think that people would mess with it. Heehee.
Or he could do the right thing and just knock on her door and ask her to move it. Sigh.