2) Someone who shamelessly manipulates others for their money - differing from a gold-digger in that a happy shopper usually pesters their friends, parents etc. rather than their partner.
3) Someone who is very good at using image manipulation programs, especially Photoshop, and often photoshops things for their own amusement.
4) Someone who obtains others' unwanted items for free.
2) Jay wanted me to lend him another fiver today, but he's not paid me back from the previous twenty times. I'm starting to think he's just a happy shopper.
3) Seen this great pic? That Jay's a right happy shopper!
4) Drag the old sofa to the kerb, some happy shopper'll take care of it.