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One Direction's collective body art is growing.  On their way to a show in Philadelphia earlier this week, the boys made a surprise pit stop in Glen Burnie, Maryland to get themselves some ink. 

The artist they stumbled upon at the Tattooed Heart Studios there, John Garancheski, is talking to "MTV" about their visit.  Garancheski said Louis and Zayn were the only members who sat down for tattoos that night.  He says Zayn gave him a photo of his current girlfriend, Perrie Edwards of British girl group Little Mix, and asked him to create a "comic-style version of her."  The 20-year-old had added specifically that he didn't want an exact replica of Perrie, he just wanted it to "look like her."  

The tattoo artist tells MTV that the heartthrobs were "such nice guys" and super cool during their visit to his studio.  

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