To save the whole "think before you ink" debacle from occurring, here are ten costumes which allow you to be a tattoo-covered beast for Halloween alone.
The costumes are pretty awesome and very realistic. You could also go the temporary route and use stick-on tattoos that you print yourself, such as the one featured charmingly on my avatar. From the tights trend below to the arm sleeve, there are so many options--what are you waiting for?
Realistic Temporary Tattoos
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DIY Body Airbrushing
Crowd Sourced Tattoo Shirts