I think around the time it got popular everywhere else. Tumblr has always been fond of shows with a rather strong undercurrent of homoeroticism. And Jojo has quite a bit of that.

like that was overtly homoerotic but there are tons of things that vary from subtle to aggressive. For example you have the incredibly buff, hypersexualized pillar men literally placing rings inside Joseph until death does them part or Johnny chasing after Gyro because he became mesmerized by his balls (like it's a stretch but it's still there) or when any of part 5 happens because that's a god damn homoerotic clusterfuck (for example, we'll take the scene where bruno talks about how he could shove anything in Gio's mouth and down his throat and he'd be powerless to stop him).