A tattoo can mean many things if you are on Earth. The most popular, by far, is the act of getting ink needled into your skin in attractive patterns and pictures. It entails going to something called a "tattoo parlour", which is a glamorous name in itself, though I have yet to see anything that resembles glamour in a place like a tattoo parlour.
One can definately expect to haggle over prices on the selected design. Most price changes are due to the intended location of the tattoo, whether it is in color or just black ink, the size of the tattoo, the intricacy of the design, and too often the attitude of the person haggling with the tattoo artist.
Another "tattoo" that one can get is a shot of alcohol in various shades of the rainbow. A "blue tattoo" is an inky blue color, that will temporarily stain your teeth, tongue, lips, and waste products. If you are not prepared for the latter, then it can be quite a surprise.
Last, but certainly not least, is the tattoo that shouts, "De Plane! De Plain!" on a ficticious tropical island. He is short in stature, and looks like he might be Hawiian. Be sure you do not get one of these, since they are quite hard to maintian.
For the longest-lasting type of tattoo, I would suggest the first one explained. Not ready for the commitment? Then choose the second, but at all costs, avoid the third. Not only does it talk, but it chases planes as well.