I’ve seen this phrase being used and it just confuses me. I wanted to see if I could find an explanation for the phrase.
A direct translation would be something like "Do it for the rest of your life," but it doesn't really make sense in some contexts. For example, in a manga, there is a couple out in the open doing the stereotypical "couple" things. Then a guy walking by will say "一生やってろ！" So I just wanted to know if there is another way to interpret the phrase.
It's often a verbal irony, in that the speaker means the opposite without saying it. So the speaker's inner thought could be "I think that's unproductive/going nowhere, I'd stop it".
Pixiv has this tag: https://dic.pixiv.net/a/%E4%B8%80%E7%94%9F%E3%82%84%E3%81%A3%E3%81%A6%E3%82%8D
In doujin context, it looks like it means something like "[you two are] hopelessly in love".
一生やってろ （一生やっていろ）Your translation is correct, but the taste of the phrase resides in the verb "yaru" (that also means "do sex"), so the phrase is a way of laughing about married couples ("do sex with that lady for the rest of your life").
It is basically a phrase that defines a single guy.
