I think plugging, as other people said, is just another, and very efficient method of drug administration, and I am NOT gay, far from it, I am actually engaged to a very beautiful young woman, (I am male), and wouldn't ever dream of being queer LOL.
I have plugged, I use the method usually to take things that taste foul (wouldn't it be a bummer to have tastebuds in your rectum

) and occasionally for a substitute IV, I find it is the BEST way to ingest harmala alkaloids if using Peganum Harmala seed, I once used it for this, and squirted 1 liter of acidified, filtered harmala brew, no nausea caused at all, no anal leakage whatsoever.
I think the tales of arse-leakage are exaggerated grossly, I have personally held up to a liter and a half of harmala brew w/o the dam breaking.
I certainly wouldn't plug anyone else, save only for my fiancee if she requested it, but on myself, it is almost the perfect administration method for many drugs.