Ah, feels nice to have an ordinary game question to answer. And to see a new person discovering the game, welcome!
Both the bosses in GT are gimmick bosses. There's a trick to them. These tricks are hinted at, at least in the case of Khazeem, via dialog. Technically he is possible to beat normally, but it takes a WHILE, and you have to manage resources very carefully and just get lucky (a number of re-tries). The trick in Khazeem's case is the hyena cologne you get from Mahir's bedside dresser. It interferes with the scent coming off Khazeem, allowing Mezz to focus. Keep in mind that this is the normal mode boss fight: the slut mode version instead requires that you use what you've learned servicing the hyenas to "finish him off", winning by sexually exhausting him.
Also, keep in mind that Openfireplace has a great text and flow-chart guide of the game stickied here. I'd highly recommend checking that if you ever get stuck, so you don't have to wait for me to reply. I THINK this is included/explained on there, can't remember.