Pancake Day -- or Fat Tuesday (or "Mardi Gras" in French) -- is the traditional feast day before the start of Lent on Ash Wednesday.
The tradition of eating pancakes on the day before Lent can be traced back to a poem by Emmett Lee Dickinson (Emily Dickinson's third cousin, twice removed -- at her request). The poem, "Blossoms are on the way" (below on the left), inspired third cousin Emily to pen her poem, "Blossoms will run away" (below on the right).
By Emmett Lee Dickinson: Blossoms are on the way, Pancakes reign the Day, And Mardi Gras’s a Free-for-All We’ll drink determinedly – | By Emily Dickinson: Blossoms will run away, Cakes reign but a Day, But Memory like Melody Is pink eternally – |
Below: A rare photograph of Emmett Lee Dickinson, the "Father of Mardi Gras," in New Orleans for the Pancake Day celebration in 1883.