Sorry,
her crotch - as in your hands will be in prime position to brush against her crotch IF she starts at the head of the table and IF she leans in. Once or twice I have been firmly told to put them by my side to prevent that from happening, but the vast majority of the times it's seen as a sign by the masseuse that you're there for what she thinks you are and occasionally she will lean in hard so your fingers can do the talking.
Sometimes the reaction has been surprising i.e. girl pulling her leggings down from the off of starting the massage and ending up being fingered while doing it.
If you leave your hands at your sides then she
may either brush her legs or crotch against them when working from that side, but that doesn't happen so much in my experience.
Seriously, at the the head of the table, always
