Quemao' is the colloquial way of saying quemado, which means "burnt". This is a common shortcut in Caribbean Spanish where the 'd' sound between two vowels is often dropped.
In the song, Pitbull describes himself as "Coco quemao'", or "burnt coconut". This is a playful slang expression that could mean he's a bit crazy or just very tan from his Miami lifestyle. It's a perfect example of the colorful, creative slang you'll find in reggaeton music.
In "Por Favor", Pitbull teams up with Fifth Harmony for a flirtatious, Spanglish party track where good manners are the ultimate currency. Pitbull starts out working his usual rapid-fire charm, peppering a girl with questions: "¿De dónde eres, cuál es tu nombre? / ¿Tienes novia, o buscas hombre?" ("Where are you from, what is your name? / Do you have a girlfriend, or are you looking for a man?"). He even jokes that he's "not too proud to beg like TLC," clever wordplay on both tender loving care and the 90s girl group TLC famous for the hit Ain't 2 Proud 2 Beg. He gets cheeky by asking for "un besito en la punta" ("a little kiss on the tip"), only to playfully dodge the dirty joke later by claiming he meant the tip of his nose, or a trip to Punta Cana, or the Eiffel Tower in Paris.
Fifth Harmony keeps him completely in check, though. Their answer is simple: he isn't getting anything until he minds his manners. They make him pump the brakes with "Please, vas a tener que esperar" ("Please, you're going to have to wait"), promising that he can have whatever he wants if he says magic word: "Lo que quieras si me dices por favor" ("Whatever you want if you say please"). Pitbull gladly plays along, throwing in Caribbean slang like "coco quemao'" (literally "burnt coconut," meaning someone who is a little crazy) and describing the vibe as satisfying "como arroz con huevo frito" ("like rice with fried egg"). It turns everyday dating into a dance where being polite is what actually closes the deal.