The Talmud in Tractate Avodah Zarah says that every afternoon, God plays with Leviathan—the colossal sea creature described in (Job 41:1) and (Psalms 104:26). The fourth quarter of God's day, from the ninth hour to the twelfth, was originally reserved for this activity.
Rabbi Yitzchak made a bold claim about divine laughter. "God does not laugh," he said, "except on one particular day"—the day described in (Psalms 2:4): "He who sits in heaven laughs; the Lord has them in derision." That day, according to the Talmud, is the day when the nations are tested and fail.
But Rabbi Yosei raised a different scenario. In the future, he taught, the nations will try to convert. The Talmud immediately objects: we do not accept converts in the messianic era. Conversions in times of Jewish triumph are suspect—the convert might simply want to join the winning side, as happened in the days of David and Solomon.
Rabbi Yosei clarified: these are not sincere converts. They are people who attach themselves to the Jewish people superficially. They put on tefillin (leather phylacteries worn during prayer), wear tzitzit (ritual fringes worn on garments), hang mezuzot on their doors. But when the war of Gog and Magog arrives, each of these superficial converts will ask Gog: "What are you fighting against?" Gog will answer: "Against the Lord and His Messiah" (Psalms 2:1-2). And immediately, every one of them will tear off his tefillin and walk away.
The passage connects God's laughter to God's loneliness. Leviathan was created as a pair—male and female—but God killed the female and salted her flesh for the righteous in the World to Come. The male was left alone. And God plays with this solitary creature every afternoon. Even the Almighty, the Talmud suggests, keeps company with what remains after loss.