It won't hurt him... I used to have a cat whose favorite foods were Reese's Peanut Butter Cups and black olives... seriously!!

I didn't give them to him but rarely but boy was that a treat... just a taste though!!

But the only bad thing is the caffeine.. if you drink a decaffeinated tea you wouldn't have to worry.. I had a cat that as a kitten would KILL to get to a glass of wine but she got over that stage because I was careful to keep it away from her and she lost the strange desire...

Good luck :o)