^
BA = Bioavailability. It's the actual amount of the drug you consume that your body absorbs into the bloodstream. Oxycodone has a high oral BA. For example injecting a drug will give you 100% BA, while snorting it may give 70-80% and oral might give 60% (this is just a random example - I'm not talking about oxycodone). It's the reason different ROA (routes of administration) can produce different/stronger/weaker effects etc.
Plugging (depending on the drug) often has a BA of 90%+ and in some cases (again depending on the drug) is the 2nd closest ROA to IV in terms of intensity.
I also echo what everyone has said, dissolve the powder into the required amount of water, suck up into an oral (needle-less) syringe, then plug. Lay on your side for ~10 mins and you're done.