... steals the best sandwiches from children's hands, while declaring "mine, mine, mine, mine"...

Animals exhibiting this behaviour are known as kleptoparasites.

Sometimes they eat the plastic lunch bag and die.

Don't forget the incessant screeching.

Thank you Ill remember this explanation as it hits the base so hard.

I also like "mushroom managing" - cover them in shit, keep them in the dark...

And sometimes they steal your french fry. Or your red Swingline stapler.

Poetic