Any direction that cannot be described by any of the standard directional naming conventions, i.e.: up, down, in, out, forward, backward, left, right, oblique/diagonal, etc.
Onward - Upward - Forward - and - Schlontzwise!!
Upon hitting the ice patch, his car started to slide schlontzwise uncontrollably.
when you're holding up your phone and making faces at it, as though you are taking a selfie, but you're really taking a picture of the person across from you or the wall or anything else that seems interesting but you don't want to be caught dead taking a picture of.
This action is often made more convincing by wiggling the eyebrows or opening the mouth, to pretend you're trying to get a Snapchat filter to work.