How I Met Your Mother
Little Minnesota
S4 E11:
It's Christmas time and both Marshall and Robin are feeling homesick in New York, and Ted's immature younger sister Heather arrives in the city. Ted has been trying to keep Heather and Barney apart because he fears they will sleep together. Barney and Heather prove Ted wrong and Ted is forced to admit that his sister has grown up.
Starring
Erin Cahill, Scott Michael Morgan, Jon Paul Burkhart