Found out that they have a policy of adding 18% gratuity for a party of FOUR or more. In all of my travels, in all of the lands, I have never seen this before (except at a private club where everything it auto-grat). I might have tipped over that amount in the first place, but the service that night wasn't very good. I think that it is probably to their discretion, if they think that the table consist of cheapskates. I scoffed at a $47 pitcher of "top shelf" margaritas, so we ordered singly. I think that I was "put in a category" and then got blown off.
I wonder how many times I have tipped on top of this tip, or even on the total amount?