Wishing someone a good meal

¡Buen provecho!

bwen proh-BEH-choh — Enjoy your meal!

"Os dejo comer tranquilos. ¡Buen provecho!"
I'll let you eat in peace. Enjoy your meal!

Said to anyone you see eating — coworkers at lunch, even strangers at the next table as you leave a restaurant. "¡Que aproveche!" means exactly the same thing.

"Walking past people eating without saying it still feels a little rude to me."— Graciela