New Yorker Diner
39 Mt Auburn St, near Watertown Sq
real late (3-4am)
You're not likely to be in Watertown when you need some late-night kibble, but if you can get there, this is a quality diner normally open for breakfast but that also opens up 11pm-4am Fridays and Saturdays. If it's busy, get a bar stool and amaze yourself to see how many pounds of butter they go through on toast.