Mero Mero
Spanish slang, literal translation: The Boss of Bosses. Actual usage is intended to infer something or someone is the very best, often with braggadocio.
"Yo soy el mero mero"; I am the top dog, the best.

"Oy abuelita! These pancakes are el mero mero!"

"Our canned menudo is el mero mero!"