I dont get why men do this? Surely the point of porn is to become aroused? Why would men want to do that in the company of other men?
They bond over the exploitation and humiliation of women. I once read a really interesting essay on this, can't remember where, though.
Watching porn is normal. Sharing it is not, IMO.
Why would watching it be normal, but sharing it be not normal? They have to get it somewhere if they want to watch it, don't they? Either they share with friends, or with anonymous strangers. Is it more normal if they pay for the porn they are given by other men?
Perhaps men watching porn with other men makes you uncomfortable, because you get the feeling that they bond over it ... you deny that they bond over the violence against women, but what else would it be?
Do you also consider it unnormal for women to recommend erotic literature or smutty romance novels to each other? Quite a lot of women must be doing it, judging from the success of Fifty Shades of Grey.
And if you consider it normal, why? According to your theory, it is all just innnocent fun, so there should be no difference, right?