Cliché: eats like a horse

Meaning: voracious appetite
Rewrite 1: eats like a teenager
Rewrite 2: eats like a starved dog
Rewrite 3: has the appetite of a wolf
Rewrite 4: can consume a leg of lamb like a piranha on a cow

Comment 1: Lots of opportunity here to have fun with the image of someone or something that can’t quite get enough to eat fast enough.

Comment 2: See what the Parents’ Common Sense Encyclopedia has to say about appetites and what is normal or abnormal.

More reading about clichés
What I found when I googled “clichés”:
• Design Clichés: “…about those symbols we use … or rather, those [that] other people use … to indicate common themes, concepts or ideas. Those symbols which have been used so often that they’ve become clichés.”