Alright, Sasori told me it was probably Itachi. I can understand completely why he wants his room back (I want mine back too) but I never lost a battle before, and I'm not starting with Konan.

So I marched off to "Deidara's" room and found out he was gone getting some food.
"Did he steal my TV?" I asked Deidara, who was sitting on his bed, sculpting some bird.
"How would I know un?"
"You're living with him!"
"So, un. I hate him."
"Have any ideas how I could get back at him?"
An evil smile crossed his face. THAT was a very very good sign.

So here's what I did. Tomorrow, he will find no food in the fridge, so he would have to make coffee. But it won't be coffee...
And I'll have a power shortage only in his room, so he can't watch TV at night.
Then, he'll be forced to either sit in the dark all night, or go to sleep and find himself on Deidara's bed again.

Thank you Deidara! And if none of this works, I have one thing that would make him never dare get in my way EVER again...Muhahahaha...