Grub

It is certainly very informal. Use it only with people you talk to in a casual and informal way.

Is it baser than terms like gulp down and I downed three hamburgers?

No, not really. It is not rude. You would not use it if you were going to a restaurant or if you had been invited to someone's house to eat. If you are going out to grab a sandwich or a burger then "grub" is fine.

Thanks LouiseT!

Wait up I was browsing through my old posts but I can't seem to find my post re: change.
And I think I wasn't satisfied with the replies I received. You probably have a better idea!

What would you tell a cashier who gave you a change of $20 instead of $25?
(I'm sorry but) My change is short!
The change you gave me is (five dollars) short!

I certainly would not say " My change is short" but then I am from Britain. I might say:-

You haven' t given me enough change.
Sorry but I think you have given me the wrong change.
This is not right
You have given me five dollars too little

Wow this is cool!

Some Americans would use the term 'short'. But Clive, a British guy, would use the terms 'enough', 'right' and 'wrong''when referring to change.

Thank you very much!