Some have a custom to refrain from cutting their sons’ hair until they reach the age of three. When their son reaches that age, they cut his hair and leave his sidelocks.
Hidden within the hilula celebration of Lag Ba-omer is another memorial: a memorial for the greatest expositor of the Oral Torah, the wondrous Tanna, R. Akiva, one of whose five greatest disciples was R. Shimon bar Yohai.
It is customary to rejoice somewhat on Lag Ba-omer. Even though we observe some customs of mourning during the omer period, nevertheless, one may sing and dance on Lag Ba-omer.
The accepted way of marking the death of a righteous person is by fasting. How then is it that Rabbi Shimon bar Yochai's expiration has become occasion for joy and festivity?