They don't even have locks on their doors! I love that place. Best drunk food besides maybe Whataburger. Whataburger wins for random parking lot fights, people watching and that chop house cheddar burger.
Try Madras Pavillion on Kirby. They are usually open on XMAS. I think a bunch of those places along Harwin/Hillcroft will also be open.
I once was in a Whataburger early in the morn in Austin when a bunch of dudebro's brought in a blow up doll with them(you know what kind I mean) and sat in a boot with said doll. They then proceeded to try to hit on the chicks in the booth next to them. Some of the funniest random sh** I've ever seen.