I put my pv in my bra. Left cup and to the armpit side. No one can see it, it can't fall out and stays relatively vertical ( unless I bend over). Unfortunately I now have a bit of a problem. Just got a provari and it doesn't fit in my bra, as the carto sticks out.
I guess you could tuck it down your pants and let it hang down one leg, but I'm not sure that's really a look you want to go for, wearing a bra and all.