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, grubis used as a noun. “Let’s get out of here and get
some food“

In example 2, grub onis used as a verb. “I could eatjust about anything..!”

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