The sideways firing thingie grew out of the gangbangers in LA. They would drive by their target, crack the window open a bit, and stick the gun out sideways to shoot through the partially opened window.
It’s also something to do with “swag”...
And when their crappy .25 and .380 semiautos failed to properly eject their fired cases, they found that pointing the ejection port toward the ground allowed gravity to help clear the empty and prevent a jam. Sometimes. Which makes it even funnier that about half the time, the movie gangstas are holding their hardware ejection port side up.
In fact, the technique goes back as far as the days of flintlock pistols, when those using handguns from horseback would sometimes carry the piece action-side topmost to keep the powder in the frizzen from spilling out while at a trot or gallop,