Do a search first... find out how your predecessors (including me) were ridiculed for asking the same question.
The answer to this elusive query is kept more tightly guarded than the secret formula for Coca-Cola. Publicly, "extras" are anything above and beyond the straight massage... NR, etc.
If you are speaking of "EXTRAS", then publicly everyone on this board will swear that they do not exist. Privately most will still protest that none of this exists. In reality, once you establish some posting credibility (I think that starts after you hit 500), maybe a kind massageplanet.netite will allude to a rumor he once heard.
Basically, you're on your own. But if you take the condom to your forehead, get a picture.