Okay, the food is really good and authentic and the restaurant is clean but the service is not too great. The waitress are very arrogant and choose how much tip they want which means they won't give your change back if they think it's a good amount to them.
I would obviously tip you, but how much I tip you is up to me and you can't take my change and decide how much you want.
Acting like this makes people not want to tip you.
Also, please don't glare at me for asking for my change back.
Lastly, don't make me eat faster because you have a long line up. It is uncomfortable to be forced to scarf down food.