Why does my kitten nurse my male cat??

For the last few days, Boo's been 'nursing' on Zorro. He'll grab a chunk of Zorro's fur(on his shoulder) and start sucking on it and kneading with his paws. He's just started doing this a few days ago, and he does it about 3-4 times a day for at least 10 minutes.
Zorro's starting to lose the hair on his shoulder now. Why does Boo insist on nursing Zorro's shoulder?? How can I make him stop?

Does Zorro mind when he does it? If he did, he would be pushing him away. You could get the kitten a snuggle kitten to replace Zorro but he might not take to it. You could put something bad tasting on Zorro, but that wouldn't be fair to Zorro when he groomed himself.

Going on a tangent for a bit: I had a kitten do that to our male Manx many years ago but he would suckle on his nipplies. After about a week of this, he actually started to lactate. My theory on why he did this is that he was separated from his mom too early. We found the kitten in a ditch when he was very tiny and think he was about 5-6 weeks old.

Zorro doesn't mind at all. He actually tries to groom Boo while he's doing it. (Zorro can't groom, so he ends up coating Boo in drool )
I could put something bad tasting on Zorro since he doesn't clean himself, but wouldn't that make his coat yucky?? Also, I don't know why he suckles on his shoulder and not on his belly??
Whats a snuggle kitten??
He wasn't weaned early either. We had his mother, and the kittens were weaned at 11 weeks. It also seemed to start after Zorro got back from being away for two days.

Hey
That's why I am here!!
We now have 6 cats!! Far too many but 3 are kittens from 2 of our cats! The mother has virtually rejected them now but now all three are nursing from their extremely loving and patient dad, Pebbles, the kittens are more than 4 months old! One of Pebbles's nipples is now enlarged and quite sore looking from all the sucking! He licks the kittens and cleans them, and when they aren't sucking they curl up and sleep together. He is neutered (this pregnancy took place in the first week AFTER he was neutered!! Just my luck!) I don't know if that makes any difference but he is a wonderful dad, bless him, but I'm glad he is not a freak. Do you think he will lactate, how can a male do that???