Does divorce occur by saying, "Upon divorce, I shall open the gas pipe," and then the opposite happens, knowing that the speaker does not understand the meaning of the word [divorce], is engaged, and has not yet consummated the marriage with his wife?

If a man utters the phrase "Divorce upon me that such and such matter is so," and it is later proven otherwise, then divorce has occurred.

If he is engaged and has completed the marriage contract but has not yet consummated the marriage with his wife, a minor irrevocable divorce (طلاق بائن بينونة صغرى) occurs. He can remarry her with a new contract, a new Mahr (dowry), a guardian, two witnesses, and the woman's consent.

If he is engaged but has not completed the marriage contract, no divorce occurs, because divorce only applies to a wife.