The model in this Times Square billboard for designer Vivienne Tam is reaching into another ad for the HP TouchSmart PC. At first glance, I thought it was another co-op ad (similar to HBO’s True Blood promotion) but look closer and you may notice that the second model is clutching the HP Mini Vivienne Tam edition. Very smart indeed. (Thanks to Lauren and Jordan for the photo.) I know I've seen this technique in print with a character from a fake ad reaching out to grab the beer in another ad, but can’t remember the brand. Can anyone thing of it or other examples?