He appears on the street, promoting the "iPogo",a fancy pogo stick with many "apps". He shows in song that the product can comb your cat, fix a flat, hang your hat and meet a boy named Matt, among other things. He gets Telly Monster to trade in his old pogo stick for a new iPogo. However, Telly returns the item, dissatisfied that it takes the fun out of jumping on a pogo stick and is able to do a special trick without its help. Mack offers him the latest model, the "iPogo 300", until he gets a call saying another new model, the "iPogo 3000", has just come out (which does everything but boing).
Mack is a caricature of Justin Long, who portrays "Mac" in many Apple Computer commercials.