When bill oddie and frank skinner are both on the davids team what is the episode?
CREATE TABLE "table1_23575917_6" (
  "episode" text,
  "first_broadcast" text,
  "davids_team" text,
  "lees_team" text,
  "scores" text
);
SELECT "episode" FROM "table1_23575917_6" WHERE "davids_team"='Bill Oddie and Frank Skinner';