I saw an avatar with a tattoo sleeve and was wondering which store has it(couldn't find it) or if it's a reward of some kind?
Masquerade, sleeveless shirt and tattoos 20,000 RP. Or you can get the long sleeve graphic tee from Trends for 1000 RP.
There's also a sleeve tattoo torso item available from the King Pins store in the bowling alley. I believe it's called Shirt with Suspenders and Tattoos if you're looking for it.