From Homestar Runner Wiki
Strong Bad's Ab-Abber 2000 helps you create abs like the professionals in "minutes—nay, seconds!" It consists of one permanent marker (not included). For a limited time only, the Cloitsterizer was offered with it, "abs-olutely" free. The slogan is "They'll be all up ons!". Strong Sad was a spokesperson, but only because Gooblies was being held for ransom by Strong Bad. Homsar also acted as a spokesperson for this product, for no known reason.
Strong Bad put the Ab-Abber on sale in garage sale for $77.00. It was also apparently one of the prizes Homestar Runner gave away in The Show, as evidenced by Main Page 19. The Ab-Abber is apparently one of the items sold by Bookazon.com, seen in the DVD version of studying. The marker-drawn abs also appeared on the first page of Strong Bad's pop-up book and in an altered screencap of Strong Bad's Cool Game for Attractive People. In Fan Costumes 2015, a picture is shown of someone wearing an undershirt with drawn-on abs, which Strong Bad refers to as a "limited-edition Ab-Ab-Beater undershirt".