When you're so fucked up that time itself has no meaning at all. Looking for the right candybar at Walgreens can take hours when you're geeking. You can spend a day trying to fold some origami model, or solve a math problem, or read a single paragraph.
Also related to tweaking.
When tweaking AND geeking, this time contraction is combined with a feverish hurry and awareness of your own "meth stench," not to mention a belief that what you are doing is of the utmost importance, and is not to be disturbed by anyone.
I was geeking last night - I must have de-childproofed about 20 lighters!