A form of shading in ink or pencil drawing\sketches, where one creates shadow or the suggestion of colour by drawing lines diagonally in one direction, and then cross-hatching them with similar diagonal lines passing in the other direction.

The more lines you do the darker the shading becomes.

Of course, I just clicked this link off the home page. It could have a whole other slang meaning I don't know.

A casual invitation / threat used by an individual that is not afraid of fucking someone up.

Neatly spaced usually diagonal lines to indicate different shades or shadows in a black and white pen and ink drawing.

The # character also called:
cardinal
comment sign
crosshatch
crunch
fence
gate
gridlet
hash mark
hex
noughts-and-crosses
octothorn
octothorp
pig pen
pound sign
resemblance
resemblance
resemblance
sharp
shibboleth
square
sulamit
tic-tac-toe
widget mark

Crosshatch

(v): To take something that was previously boring, unoriginal, or old, and visually revitalize or renew it.