1. To scrape off the outer layer of skin (from something). A noun or pronoun can be used between "skin" and "up." I skinned up the palms of my hands when I fell off my bike.He skinned his elbow up when it scraped against the brick wall.
2. To hand roll a cigarette, especially one filled with cannabis. Hey man, you want to come by and skin up a little later?He always goes to his car on his lunch breaks to skin up.
skin up
v.
1. To bruise, cut, or injure the skin or surface of something: He fell off his skateboard and skinned up his knee. She slipped on the sidewalk and skinned her arm up.
2. To roll a cigarette: I pulled out a pouch of tobacco and skinned up.