Phineas and Ferb's Quantum Boogaloo

"Phineas and Ferb's Quantum Boogaloo" is the 25th broadcast episode of the second season of Phineas and Ferb and the 72nd broadcast episode overall. It originally aired on Disney XD in the United States on September 21, 2009, and later aired on Disney Channel on September 25, 2009. In the episode, Phineas and his stepbrother Ferb travel into the future and have their time machine stolen by their older sister Candace, now an adult, who travels back in time to get her brothers in trouble during one of their outlandish schemes. In doing so, however, she sets off a chain reaction leading to a dystopian future ruled by the evil Dr. Doofenshmirtz.

"Phineas and Ferb's Quantum Boogaloo" was written by Scott Peterson and directed by Zac Moncrief. The episode was conceived as a means of expanding the time machine plot that was introduced previously in the episode "It's About Time." Dan Povenmire and Jeff "Swampy" Marsh, co-creators of Phineas and Ferb, centralized plot elements to satirize time travel films, such as The Time Machine (1960) and the Back to the Future trilogy (1985-1990). Multiple scenes in the episode were meant to be rather confusing and difficult to understand in order to interest viewers so they would watch the episode multiple times, trying to learn something new each time.

The episode received generally positive reviews from television critics. In its original broadcast, it ranked fourth in the key demographics Boys 6–14, Kids 6–11 and Boys 6–11, totaling 599,000 viewers, an 88 percent increase from that of the previous year's ratings in the timeslot. When the episode premiered on Disney Channel on September 25, 2009, it was the thirteenth-highest-ranked cable program for the entire week. The episode guest starred actors Jennifer Stone, Moises Arias, Noah Munck, and Jennifer Grey, along with the band Bowling for Soup, who appeared as themselves performing an extended version of the series' theme song, "Today's Gonna Be a Great Day," which was also included on the official Phineas and Ferb soundtrack, which was released on September 22, 2009.