I've always taken it to mean "Keep lewd 3D stuff out of /a/, and don't blogpost unless it's in a designated drunkthread."
Go to Japan and have some neat experiences and pictures to share? Make a thread and watch it become the most worthwhile thread on /a/ for a month.
Go to your nearest bottle depot and witness hobos as you try to get $30 from recycling your bad habits? Keep that shit off /a/.
Talk about how 3DPD is awful, how you can understand why 3D can be tempting, how you've maybe lost your wizardry? If in the correct thread, sure. If you get banned for that then appeal or post on /ameta/, it'll get noticed by the meidos, hopefully.
Talk about how you watched the latest animu series with your girlfriend/wife? That's 3DPD. You don't need to mention 3D when appraising 2D.
These are fairly simple rules. I once mentioned I was engaged at the time in a r/a/dio thread more than a year ago, and I didn't get banned. A lot of people felt sorry for me, but it played into the current music. But randomly mentioning that in a discussion about Flying Witch or something? That's a ban, so I don't do it.