'Jacking up' is the state in which a person/hobo/fugitive finds himself somehow getting involved with injecting heroin, a really bad drug, also a really stupid way of ingesting a drug. 'Jacking up' is sometimes referred to as 'stabbin' da veins'
Jalentine posted a photo of himself 'jacking up' which means he is a real badboy and he also got a tattoo and now he is fell over because he did too much heroin.
When you have to pee in a movie but don’t want to miss anything, and must do the following mental equation: will the amount I have to pee cause enough discomfort to diminish my attention capacity for the remainder of the movie to an extent which is greater than the amount of the movie I would miss by making a mad dash to the restroom.
I saw Satantango last night, wonderful film but by the 5th hour I had to start doing pee calculus.