A birthday party was a party held to celebrate one's birthday.
On the night of 1 February 2007 of Pete's World, Pete Tyler threw a 40th birthday party for his wife Jackie Tyler, though she insisted it was her 39th. Among those in attendance was the President of Great Britain, while the Tenth Doctor and Rose Tyler of N-Space posed as waiting staff. Following the orders of John Lumic, a group of Cybermen "crash[ed]" the party and, when the President refused the upgrade, murdered him as well as the majority of the party guests. While Pete escaped with the Doctor and Rose, Jackie was captured and upgraded into a Cyberman. (TV: Rise of the Cybermen/The Age of Steel)
Mr Smith faked an image of Luke Smith, purportedly "Ashley Stafford", being thrown a birthday party by who appeared to be his parents, Jay and Heidi Stafford. (TV: The Lost Boy)
During the stay of the Eighth Doctor, Liv Chenka, and Helen Sinclair at 107 Baker Street, Liv and Helen threw a surprise birthday party for the Doctor based on the fake birthday he had given to Tania Bell upon their arrival. Liv baked a birthday cake—which, per Helen, might not have been entirely edible—Aisha Akhtar provided catering, and Ron Winters performed a conjuring act. (AUDIO: Get Andy)