Pee-Wee reads Pee-Wee Mad Magazine
http://www.madmagazine.com/sites/default/files/files/2011/08/MAD-Magaz ine-Pee-Wee-Herman-Celebrity-Snap.jpg
This photo looks to have been taken in late 1987, during production of season 2. The issue is from September 1987, and must have gone on sale a month prior.