I plug Subs. I don't plug MDMA cuz I find that its just as good as oral and it's just not convenient. I'd have to bring the gear with me to the club and I never roll at home. I like to take it just before I enter the club, in my car so plugging is just not a possibility and oral MO is just as good for this substance.
I have a spoon that I just use for that. I put a piece of sub on it, add water, crush it with the back of the syringe, mix it up, suck it up into the syringe, put some lubricant on the tip of the syringe and plug it in. I prefer the lubricant, it makes the whole thing painless. It's totally uncomfortable w/o it.
Definitely feel a social stigma associated with plugging. I told my mom I plug subs, she told my f'n doctor. Then they both tried to explain to me that I shouldn't do it. Well whatever, I'm not gonna put that nasty orange crap under my tongue for 30 minutes. I'd puke. So now I just keep it to myself, my husband and BL.
I also plug antibiotics. They totally kill my stomach and make me vomit. When I plug, there is no negative gastrointestinal side effects. No nausea, no vomiting.
For some drugs plugging is just a better option. Not for all drugs, but some are just better plugged.