Pike's Birthday was the annual observance of Christopher Pike's day of birth. By the late 24th century, it was celebrated as a holiday in the United Federation of Planets.
In 2259, a time traveling Bradward Boimler from 2381 inadvertently revealed to Erica Ortegas and Christine Chapel that Pike's birthday was a holiday in his time.
Pike viewed his birthday that year as particularly notable, as it was the first year he surpassed his deceased father's life span. Initially, he did not want a surprise party to celebrate the occasion, but with the assistance of Boimler, he realized he should spend it with his friends, especially given the knowledge of what his future would be. (SNW: "Those Old Scientists")