Sorry to be dull but....
This is what it looks like to me.
Someone with surgical gloves on is injecting something in her ass - could be B12, could be a painkiller before a tattoo. I certainly don't know of any rec drugs you inject into the butt cheeks nor do I know any junkies that use surgical gloves.
The shot with the 'tourniquet' is a tad dumb. I'd guess that's a hairband she's got around her wrist or even possibly a watch/dress jewellry. The tourniquet is in the wrong place for someone jacking up - it should be on the upper arm. My guess is she's was just posing with the needle because she is slightly retarded and has a severe lack of foresight.