Full of energy like a young horse. Has sexual undertones too.

In the US, "feisty" means "quarrelsome."

Have you always been this tough, agressive, ready to conquer the world or bite someone, on fire, with lots of energy and guts?? :)

The word 'feisty' is also used nowadays to describe a woman who is either opinionated and aggressive or high spirited. The word originates from a combination of the Old English word fyst meaning to fart or pass wind and the German "fist" meaning a small excitable dog.