"As we barrel towards our inevitable demise, we wilt, and our bodies deteriorate, and it's this really sad dark thing. And that process is well under way for me.
"[The boob job] came from me being legitimately horrified to look in the mirror and discover that not only am I developing man tits but I literally have underboob too. And so I'm childishly lashing out at the god that enabled me to develop man titties. Like, if I'm going to be forced to have titties then god damn it they're going to be DDs."
And as for the penis tattoo, well, Steve-O said he hopes it'll detract from his ageing face.
"The penis tattoo follows a similar line of thinking. I feel compelled to draw attention away from the increasing wrinkling going on around my eyes," he said.
"Clearly, a big dick on my forehead is all anybody's going to be able to see, so it'll keep me young."
It comes after Steve-O made headlines in December for launching his own X-rated site, Steve-O Raw, which contains NSFW photos and content.
"I've become incredibly frustrated with all of the 'community guidelines violations' I'm constantly getting in trouble for on my social media platforms, and that's my main reason for doing this," he told The Sun at the time.