R. Crumb's Keep on Muffin'
Wikisimpsons - The Simpsons Wiki
R. Crumb's Keep on Muffin' is a muffin store that opened on the same block as Edna Krabappel's muffin store, Edna's Edibles, along with 'Muff Said, H.R. Muffin Stuff and Muff Mart.