20%: Beelzebub (Patreon)

One of the Seven Princes of Hell, Beelzebub has always been a good businessman. The Lord of the Flies, as he is sometimes referred to, opened up his restaurant as a fried-bat chain during an economic boom. Beelzebub's, as it was known, fell prey to a recession and saw many of its stores close. Sensing an opportunity, the demonic mogul shifted the company's focus and it became a fast-casual TGIFridays style hot-spot in resort towns such as the one residing on The Lake of Fire. 

The various of denizens of Hell quickly became loyal customers, as they enjoyed not only the variety of good food, but the fact the employees who worked there were being punished for eternity. The big-screen tvs showing Headball Games didn't hurt, nor did the 10cent wing nights. And as for leaving tips? Optional. Just don't ever get too generous. We all know what happens if you leave 20%...