Who is Big Metra? Óscar Castro Flores is a Mexican rapper of Puerto Rican descent who was born in Mexico D.F. in 1976. Musically, he’s known as one of the fastest rappers in the world according to his candidacy to the Guinness Book of World Records. With more than 12 years in and out of various hip-hop outfits, Big Metra brings his accelerated approach to hip-hop with his solo debut A Otro Nivel, on which he wrote and produced a majority of the songs. There’s a one-two combo of hip-hop and reggaetón but the nitty-gritty comes when Metra shows off his fast-paced flow. His tongue-twisting technique is impressive as well as breathtaking. The first single, “La Crema,” is a hit on both the hip-hop and reggaetón versions that are both included.