Lag Ba’omer is special in that the prohibitions of the Omer period may be suspended for the day, or cease, according to one's custom. It is a time of dancing and singing.
In Meron (Israel), the burial place of Rabbi Simeon bar Yochai and his son, Rabbi Elazar bar Simeon, tens of thousands of Jews, if not more, gather to celebrate on the "Yahrzeit," (or more properly, the Hillula [Hillula of Rabbi Shimon Bar Yochai]) the anniversary of the death of the "G-dly man," the great scholar who lived in the immediate aftermath of the Second Temple. With torches, song and feasting, the Yahrzeit is celebrated. This may seem somewhat odd, but was a specific request by Rabbi Simeon bar Yochai of his students. It is a custom at the Meron celebrations, dating from the time of Rabbi Isaac Luria, that three-year-old boys are given their first haircuts or Upsherin, while their parents distribute wine and sweets.