Off-target, wrong, or undesirable effect.
We were going to have a great night. We had three kegs of beer, enough guns and ammo to occupy a small country, and a little thermite (just for fun). That's when everything went sideways.
adj. The orientation of an asian woman's vagina.
Kim shaved two dots into her bush and made a smiley face with her sideways vagina.
to become extremely and uncontrollably drunk, high or just plain messed up
Dude, i was so sideways this weekend.
Adj. Used to describe a state of varying levels of inebriation.
Dude, after that ninth beer I was totally sideways
The act of getting ones automobile to drift.
Man did you see that! he got the fattest sideways around that bend!!
In recorded music, the attribute of one song sounding like another because of similar beat, melody, singing voice(s), etc.
"Spanish Dancer" by Stevie Winwood is "Empty Pages" by Traffic sideways.