CREATE TABLE table_21431 ("Episode Number" FLOAT, "Air Date" CLOB, "Event 1" CLOB, "Event 2" CLOB, "Event 3" CLOB, "Event 4" CLOB)

On what date was the episode aired where event 2 was Hang Tough?
SELECT "Air Date" FROM table_21431 WHERE "Event 2" = 'Hang Tough'
SELECT "Air Date" FROM "table_21431" WHERE "Event 2" = 'Hang Tough'