On what date was the episode aired where event 2 was Hang Tough?
CREATE TABLE "episode_events" (
  "episode_number" real,
  "air_date" text,
  "event_1" text,
  "event_2" text,
  "event_3" text,
  "event_4" text
);
SELECT "air_date" FROM "episode_events" WHERE "event_2"='Hang Tough';