In a multiplayer game select the restaurant. Get to the area where the sniper rifle is placed. Jump onto the small crate by the entrance to the Buddha-looking statue. Jump onto the stone railing (you can use this new area to snipe) and proceed to jump onto the railing that is slightly higher than the one you are standing on. Carefully walk across this area or you will fall. When you arrive at the far corner, jump straight ahead. You should land in an area where you can kill people passing at the sniper rifle.
N.B. Unfortunately the only way to get out of this place is to gt a friend throw a grenade at you from afar.
Whenever going to the dojo to learn new kata, simply use the hammer or baby scorpion move instead of using the move you are supposed to be learning. You will get 50 respects per hit and you can go on for as ong as you like. When you are finished, simply do the kata you are supposed to be doing and when you are done you will have a load more respect points.