Short for "Shit my pants I laughed so hard." Also used as IJSMPILSH (I just shit my pants i laughed so hard). The phrase can be used as a more expressive and more graphic version of the classic 'lol' or 'rofl.' This abbreviation was created by Axel K. and Josh H. during biology class in 2006.
SomeGuy46: ugh i just sneezed on my screen.
SomeGuy46: screw u.