Grub/Grub on

Context #1

I'm so hungry! Let's get out of here and get some grub!




Context #2:

I'm so hungry! I could grub on just about anything right now!

Explanation:
the word grub can be used as a noun or a verb. 
In noun form, it means food. In verb form, it means eat. 
In example 1, grub is used as a noun. "Let's get out of here and get some food"

In example 2, grub on is used as a verb. "I could eat just about anything..!"