Window air conditioning?

i have a window air conditioner and my dad is being an a$$ insisting that i have to move my bed so that he can put it in the window closest to the outlet, well i have an extension cord that just happens to reach my other window so i wouldn't have to rearrange my room. he says you can't plug it into an extension cord, please please tell me he's wrong i like my room the way it is minus the heat. please help