RISK to POOP.

Every letter change

1. RISK → RISE: change letter 4 from K to E.
2. RISE → ROSE: change letter 2 from I to O.
3. ROSE → POSE: change letter 1 from R to P.
4. POSE → POME: change letter 3 from S to M.
5. POME → POMP: change letter 4 from E to P.
6. POMP → POOP: change letter 3 from M to O.