A slang term for the food served at a pub or bar. Usually it is fast food, grilled or deep fried. Sometimes it is even a frozen pizza cooked in a toaster oven. Salty popcorn is often offered as free pub grub (to encourage drinking.)
Many drinking establishments servepub grub and some actually have some really good food!
When you do nothing but jack off and eat all day. Not necessarily in that order. Usually associated with a porn addiction.
I never see John any more. Has he been working a lot? Working? The guy's a rub and grub. He never leaves the house and he pays for his porn accounts with his food stamp money.