Death grip syndrome is a major problem with porn addicts, particularly those who have been abusing porn for years and masturbating (as these two often go hand-in-hand) and the desensitization that goes along with it.
What is a death grip?
Death grip is the increasing constriction of the penis and applying more pressure as a degree of desensitization has set in and the addict must constrict it further to have any sensation at all during masturbation.
And I find it detestable that in Googling "death grip syndrome," a bunch of articles populate that make light of it (as you know we live in an enablist and apologist culture that streamlines porn use at every turn). They are normalizing this malady that's making millions of men impotent. They are poking fun at women for believing this is a problem that even exists at all in men.