Quick taping aim+ fire shoots your own character and you start bleeding. ( happens if you aim +/- 20° on vertical Y axis )
If you quickly spin around and quick tap the aim+fire in any direction, you'll shoot yourself again.
If you hold fire on automatic weapons and quickly spin around, you'll shoot yourself.
(posted this one before but it doesn't show it anywhere)
Blowing into fire makes "puke" sound.