"Cat Splat Fever" is an episode of The Itchy & Scratchy Show.
Scratchy discovers a suicide note from Itchy, then sees Itchy jumping into a well. Scratchy jumps into the well after Itchy to save him. But it's a trick: Itchy has landed safely on a protruding brick just below the rim of the well. Itchy smiles and waves at Scratchy as he passes by, and Scratchy falls to the bottom of the well where a waiting alligator devours him. Scratchy's angel rises toward the top of the well, but just as he passes Itchy, Itchy draws a gun and shoots him. Scratchy's angel then falls back into the well.
After the cartoon ends, the final frame says "Dedicated to Timmy O'Toole."
This is a parody scene from Disney's Peter Pan, were Captain Hook fell into a crocodile.