Otherwise known as "Pentecost" for those of a less Hebraic persuasion.

Shavuot, also spelled Shavuos (Hebrew: שבועות (Israeli Heb. [ʃa·vu·'ʕot], Ashkenazi [ʃə·'vu·əs]) "[seven] weeks"), is a Jewish holiday that occurs on the sixth day of the Hebrew month of Sivan (corresponding to late May/early June). It marks the conclusion of the Counting of the Omer and the day the Torah was given at Mount Sinai. It is one of the three Biblical pilgrimage festivals (shalosh regalim) mandated by the Torah.Shavuot, also spelled Shavuos (Hebrew: שבועות (Israeli Heb. [ʃa·vu·'ʕot], Ashkenazi [ʃə·'vu·əs]) "[seven] weeks"), is a Jewish holiday that occurs on the sixth day of the Hebrew month of Sivan (corresponding to late May/early June). It marks the conclusion of the Counting of the Omer and the day the Torah was given at Mount Sinai. It is one of the three Biblical pilgrimage festivals (shalosh regalim) mandated by the Torah.

To be honest, I'd like to get involved in one of these all night Torah study sessions, but I don't think I'd be a very popular figure if I showed up.