Seriously, don't try DIY lip-enhancing treatments. Just don't.

Oh, humanity, when will you learn?

Inspired by Kylie Jenner’s pillowy pout, young women and men all over the internet have been sucking on bottle caps and shot glasses to make their lips swell up, with some absolutely disastrous results. Check out the #KylieJennerChallenge hashtag on Twitter and Instagram and you’ll see countless photos of sore, bruised, comically inflated mouths — surely a far cry from what they had in mind.

Here are just some of the ‘after’ shots. (Post continues after gallery.)

This comes just months after Perth woman Brittany Forster made the world cringe (and, okay, laugh a bit) when a Candylipz lip-plumping device left her with an inflated, bruised pout. And good on her for sharing.

It was an important reminder that if a DIY beauty procedure seems too good to be true, it probably is. Especially when it comes from the internet.

However, it seems no amount of common sense or cautionary tales are sufficient to deter some people from pursuing their dreams of pillowy lips.

Just a month after Forster's painful Candylipz experience came a sorrowful tale of two Icelandic sisters who decided to take pout enhancement into their own hands and ended up extremely blue and bruised.

Not pointing fingers. but it seems Kylie Jenner's lips are partly to blame for all these disasters. (Post continues after gallery.)

Rather than purchasing a gadget online, Yrja Ás Baldvinsdottir and her sister Bir­gitta Ás tried repeatedly sucking into the lid of a plastic water bottle, having seen the technique floating around on Facebook.

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A quick Google search reveals several beauty blogs encouraging readers to try this approach, so you can hardly blame the two women for thinking it was an okay thing to do.

Alas, it wasn't. Presumably the result they were after didn't involve serious bruising and swelling, but that's what they got. On the bright side, at least they didn't pay to look like they'd been punched in the mouth.

"I just wanted to try it and see what they would look like, I've never done it before, and I won't be doing it again. It was very, very painful. My lips turned blue," Yrja Ás wrote on Facebook.

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"I wanted to warn people against do-it-yourself lip expansion, but was really surprised and shocked that it ended up being something that loads of people were copying." The sisters had posted about the technique on a Beauty Tips Facebook page, which spurred a number of other people to try it.

Speaking with The Daily Mail, cosmetic surgeon Pordiis Kjartansdottir warns that bruised, blue lips are only the start of what's wrong with this technique.

"The lips turned blue because blood fills up and they could easily become infected and lose all sensation. It is a really dangerous stunt and I'd advise strongly against anybody trying it," she said.

So yeah. Just don't go there, friends.

Have you ever had a DIY beauty procedure go horribly wrong? Tell us everything.