In Tractate Ta'anit Page 22 Page A it's written about two people who made people happy and merited because of it a share in the world to come... How did they make other people happy?

The Maharal (Netivot Olam, Shalom 2) explains that they would belittle themselves, apparently making fun of themselves or using self-deprecating humor, so that the depressed will laugh and be happy. R. Moshe Pizenitz (Darash Moshe in Chidushei Geonim) believes they brought joy through words of Torah, for he finds it hard to believe that they were just comedians, but others don't mention that as problematic.