How I Met Your Mother (HIMYM) TV Series
Season 03 - Episode 09
Explanation about "Ted and Robin at the Carousel"
The episode ends with a shocking response from Barney to Ted, saying that "I saw you and Robin at the carousel!"
For those who can not remember the scene; it is about the tense moment between Ted and Robin in last episode of the 2nd Season, when Ted was helping out Robin to find her locket at the university campus. At the most dramatic moment; it was raining, Robin was crying, they were holding hands and looking to each other in a emotional way.
The carousel, which Barney is referring, was not actually in the scene at these important moments. At the beginning of the episode, there was a flash back; Robin was young and walking with her Dad at the same place. You can see a carousel in the background.
Here is a youtube video of the moment that Barney pointed out :
