The tattoo removal process is performed through a series of laser treatments (which can take up to four to 10 sessions), wherein the tattoo pigment absorbs light, which causes the ink to break down and be absorbed by our immune system, says Melissa Doft, a New York City-based plastic surgeon. (We also learned this interesting tidbit in a recent Buzzfeed report.) Although many people may think lasers simply fade the tattoo ink (similarly to how ink on paper simply fades if left in the sun), it's actually a little more complicated.

After the laser-removal process, which Doft notes, typically works best on darker, older tattoos, the ink is recognized as waste within the lymphatic system and discarded via either sweat, urine, or fecal matter. "The focus of the laser treatment is to disintegrate the ink particles of the tattoo," says celebrity cosmetic dermatologist Paul Jarrod Frank. "A high-intensity light beam is targeted at the pigmentation, causing it to break apart, become absorbed into the body, and be excreted through the body's natural immune system."

The effectiveness of the removal is partially determined by the location of the tattoo, says Frank. "Places in the body with the most circulation most easily wash away the pigmentation, while places with low circulation (like the fingers and toes) are typically harder to treat," he says. The treated area can become sensitive post-procedure, which can result in stinging, allergic reactions, and small bumps. Frank says these reactions are a result of the dissection of ink nanoparticles that occurs during treatment, and scientists are currently researching the effects of the procedure.

Bottom line: Even after laser removal, your tattoo isn't completely gone. That is, until you, ahem, excrete it. But, don't worry, it's not something you'll notice the next time you use the restroom — no matter how big the tattoo was. As Buzzfeed points out, "you will not be able to tell that there's tattoo ink in your poop — so please don't go looking for it."

Slideshow: The 50 biggest diet and exercise fads of the past century (Provided by Cheapism) 

MAYBE THIS ONE WILL ACTUALLY WORK: Americans have always had an insatiable appetite for diet and exercise programs. From gadgets and videos to shakes and meal plans, most come and go, while others refuse to die. Here are some of the most memorable fitness crazes and fad diets that have tempted consumers over the years. The 50 Biggest Diet and Exercise Fads of the Past Century