My bunny does this too but to my bed. Usually I try to catch him as soon as he starts to lift his tail up and either distract him or bring him to his litter box. And when I'm not in the room I just shut the door so he can't get in. Not sure why they do this though- maybe because it's a soft...
I will be moving to the UK in a few months and am having a very hard time deciding what to do with my buns. I absolutely want to take them with me, however I am not too keen on the idea of putting them into quarantine for six months. I was thinking that I could fly into another country in the EU...