I'm going to bring food from a different restaurant into another restaurant
I'm really curious as to why you'd want to bring food from one restaurant into another?
Because I'm too lazy to wait for a table
That's probably against their rules and also just rude to eat another places' food at their business. I imagine they might ask you to leave if you go through with this.
This would be a good business decision on their part, then
Does that mean that you're not going to do it? Because it is reasonable that you will just get kicked out, and I don't think that you'd want to waste your time like that.