It has to stop.
There is nothing innate about jewelry which makes it somehow the official property of women. You don't have to clarify between "jewelry worn by women" and "jewelry worn by men." It's just jewelry, all of it.
There is no magical property within eyeliner which turns it into a different product when it is worn by a man. It is eyeliner. It is not exclusively made for, or worn by, women. Neither is mascara.
These objects are gender-neutral. They're just things. Eyeliner is still just eyeliner, no matter who wears it.
"But it's just some harmless wordplay!" you protest. "Eye rhymes with guy! It's cute!"
Perhaps my definition of harmless differs from yours. You see, when you call it "guyliner," you're differentiating it from "eyeliner." Which denotes that eyeliner is the women-only version. Eyeliner, therefore, is for women. Make-up is for women. Men who wear make-up and eyeliner are different. Weird. Freaky.
This is called gender policing. Women are like this, men are like that. Women do these things, men do those things. Never the twain shall meet! But what happens to all of the wide majority of people who don't fit neatly into their tidy little gender categories? What about women who don't fit into all of the women traits, or men who don't fit into all of the men traits? What if women do men-things and men are into women-things? They get harassed. Bullied. Abused. Killed.
There's a lot more to gender than some rigid binary, and when you start to police gender, you end up hurting a whole bunch of people.
The big things in the world are related to the little things in the world. You call it guyliner. It feeds into gender policing. Which makes life very unpleasant for a whole lot of people in a very real way.
Maybe you could skip the cute little wordplay next time and just call it eyeliner.
Oh, and while we're at it? What the hell is up with women wearing "pants suits?" They're not called "pants suits" when men wear them, are they? No, then they're just "suits." Let's just call them "suits" when all people wear them, okay?
Nice talking to you!