This 2010 marathon had SpongeBob SquarePants and The Fairly OddParents air from 12:00 P.M. through 6:00 P.M EDT. It ended after 2013. There would also be another SpongeBob/Fairly OddParents marathon in Canada in 2013 under the title FairlyOke SongPants Day. The only difference is that the latter aired mainly music-themed episodes.
YTV Promo - SpongeOdd SquareParents Day (2003)
YTV (2004) - SpongeOdd SquareParents Day Promo
Sponge Bob Square Pants Fairly Odd Parents 15 Sec. Promo
Sponge Bob Square Pants Fairly Odd Parents 30 Sec. Promo