I asked a nice open-minded bioguy for help with mine, if you can hunt one down to assist you, well, they've got years of experience with where to put their junk, so they're probably your best resource! (you may have better luck with asking a gay friend, a straight one might find you asking for troubleshooting tips more than a little odd!) A little embarassing asking for help, but glad I did. I wasn't quite sure on the vertical, either.
Shaft to the left for easy grabbing though the fly by most right handed guys in y-fronts, even if you have no intention of doing so or aren't wearing anything with an open fly because you don't want it to fall out, I didn't have a leftie handy so I can't confirm that they dress right sometimes/always/usually-but-not-in-briefs-cause-it'll-fall-out/depends on said leftie? That seam in your pants can hurt more if you sit down and it's straight down and your jeans are a bit too tight...even though you can't really feel yours in the same way. And packers tend to be "showers" rather than "growers", so...
Underwear's cheaper in the boy's section, so I second the recommendation of shopping there - boys grow bigger than girls, but it wasn't immediately obvious to me that just because I could no longer fit in stuff in the girl's department that it didn't necessarily mean I couldn't fit in the boys!
