What is Jack-knife?
1.
another term for a rude person, synonymous with asshole, jerk, dick, bastard
a way to curse without offending your grandparents
1) Dude, look at that jack-knife over there, what a douche!!
2) Quit being a jack-knife!!
See
2.
Having deposited your turd in the toilet, you look back to discover that its poking out of the water, too long and solid to go round the u-bend.
I had to go and fetch a stick so I could break up the jack-knife and flush the little devil.
