Skinny, nicely shaped legs that usually resemble the legs of a frontman of a Pop Punk band, hence the term "Pop Punk legs". Usually the person wears Shorts/Skinny jeans with Vans, Converse, Toms, etc.
Me: "Hey you have really Pop Punk legs!"
Random guy: "Uh... Thanks?"
Me: "They're just skinny and nicely shaped,"