Can u smell what the rock is cooking?

Ah, this one is funny, mate. It is not about real food. The Rock is a famous wrestler and actor. He says this in the wrestling ring. When he says he is 'cooking', he means he is getting ready for a fight. He is preparing to beat the other guy. So, can you smell it? It means, do you know he is about to win? It is his famous saying. I reckon it is very cool.