In some cultures close male friends kiss -- as in a peck on the lips or on the cheeks. In North American culture, men kissing has traditionally been a taboo. So for a lot of men I suppose it would depend upon who did the kissing and what sort of kiss they gave.
For me, it would depend upon whether I invited the kiss, whether I'd let him kiss me before (or whether I'd kissed him before,) or whether he came from a culture and/or upbringing that traditionally kissed other males. (So we're back to whom and how.)
Now, were it a stranger, out of the blue? I'd probably deck him. I don't treat other men, nor women, that way, and I don't want to be treated that way, either. If I wanted to be polite about it, or he was a friend of a friend, I'd probably warn him not to do it again. Once. Just like with any other form of non-accidental unwanted contact. Assault's assault, and I don't like being assaulted. I doubt many people do, regardless of gender.
(And yes, some forms of straight male interaction encourage things like ass-grabbing or crotch-grabbing. Notably some sports groups. I never liked getting groped by strangers in gay bars, and I don't like getting groped by non-strangers unless I invite it. 'Nuff said. If you happen to like it, that's fine with me. You can get all the grabbing intended for me. Thank gods it's lessened a lot, now that I'm older and not the 'pretty' looking boy I was in my youth.)