do you tip at resturants?

I tip 15 to 20 % usually unless I have to wait for tea and my bill when i,m done then I may go as cheap as 10. but if service and food is xclnt i may go 25 0r 30. I have a little mexican restaraunt I frequent and every few times i go I slip the hostess a five or ten and its funny when the lines out the door I never seem to wait long and always get a booth. The waiters know me and keep my margaritas full and my wife gets loopy off her crown and cokes. I suspect theyre loading them up. Every one likes to get greased. If I cant afford to eat and tip I eat at home.