Popping Tags basically means to go shopping. This is most often used when going clothes shopping. Popping tags refers the removing of price tags attached to clothing items. When these price tags are removed, they make a popping or snapping sound.
The video above shows “Thrift Store” from American rapper Macklemore. In the chorus of this song you hear the words “I’m gonna pop some tags“. This video has an element of humor to it. The slang term “popping tags” is traditionally used when spending large amounts of money. However, in the video Macklemore raps about buying things at a thrift store (second hand store), where used things are sold for a very cheap price.