This is actually technically true — the ingredients listed for chili con carne include a "flavor enhancer" with sub-ingredient silicon dioxide, which is what sand is. Idk where food-grade SiO2 comes from (probably not, like, BEACH sand) but it's a verifiable fact that Wendy's chili has sand in it.

Also, like, it's on the assignment to explain WHY people might eat sand (gives texture! keeps powders from caking! possibly other reasons!) and not just fearmonger about fast food w chemistry gotchas