One of the sages, a man named Rabbi Beroka, was often visited by Elijah the Prophet.

(After Elijah left this world he became an angel of sorts. He often comes down to earth to fulfill some mission or other, though he does have some standard jobs, like attending everyone’s Passover Seder and circumcisions. Otherwise, he does other stuff and hangs out with Rabbi Beroka types.)

Once, while Rabbi Beroka was in the marketplace of Bei Lefet, Elijah came along to visit him. Rabbi Beroka took the opportunity to ask Elijah about the character of the people in the marketplace. The report was not very positive. But then two men strolled in and Elijah pointed to them said that they had great merit. They looked like ordinary people so Rabbi Beroka went up to them for a short interview:

“What is your occupation?”

“We are comedians,” they said. “Whenever we see people who are sad we go and cheer them up. And whenever we see two people who are in a fight, we work really hard to make peace between them.”

Rabbi Beroka probably thanked them and went back to Elijah. He also had probably gained a whole new perspective on how to judge (or not to judge) people and the importance of being happy.

Source: Babylonian Talmud, Tractate Taanit, page 22a.

On the other hand, there are other talmudic statements that imply that too much joking around can lead to no good. It seems that jokes themselves are neutral—neither good or bad. If you use them for a good purpose, like cheering people up, then they’re a good thing; if you use them for a bad purpose, like fooling around and avoiding any sense of seriousness, then they’re a negative.