I don't know if it's a font or not, but I see a lot of tattoo artists use it..

I would guess it is handmade by each artist. But if you search for "Sailor Jerry font" on Google I think you will find something similar

or here:

http://new.myfonts.com/morelike/99730/

Similar (here @ DaFont):
- Tattoo Ink
- Sailor Larry