How I Met Your Mother: 4x21
The Three Days Rule
Ted breaks one of Barney and Marshall’s relationship rules, texting a woman he recently met, so the pair play a joke on Ted by pretending to be the woman.
4 - 1Do I Know You? Sep. 22, 2008
4 - 2The Best Burger in New York Sep. 29, 2008
4 - 3I Heart NJ Oct. 06, 2008
4 - 4Intervention Oct. 13, 2008
4 - 5Shelter Island Oct. 20, 2008
4 - 6Happily Ever After Nov. 03, 2008
4 - 7Not a Father's Day Nov. 10, 2008
4 - 8Woooo! Nov. 17, 2008
4 - 9The Naked Man Nov. 24, 2008
4 - 10The Fight Dec. 08, 2008
4 - 11Little Minnesota Dec. 15, 2008
4 - 12Benefits Jan. 12, 2009
4 - 13Three Days of Snow Jan. 19, 2009
4 - 14The Possimpible Feb. 02, 2009
4 - 15The Stinsons Mar. 02, 2009
4 - 16Sorry, Bro Mar. 09, 2009
4 - 17The Front Porch Mar. 16, 2009
4 - 18Old King Clancy Mar. 23, 2009
4 - 19Murtaugh Mar. 30, 2009
4 - 20Mosbius Designs Apr. 13, 2009
4 - 21The Three Days Rule Apr. 27, 2009
4 - 22Right Place, Right Time May. 04, 2009
4 - 23As Fast as She Can May. 11, 2009
4 - 24The Leap May. 18, 2009