Ted uses "Nimrod" as an insult. Originally "Nimrod" was an Old Testament king famed as "a great hunter before the lord" which led to Nimrod connoting a skilled hunter. In 1933 Bugs Bunny sarcastically referred to the inept hunter Elmer Fudd as a 'little nimrod'. One smart-ass line from Bugs reversed a linguistic tradition dating back 2500 years.
Sock, upon seeing Kendall, says, "I know a brother when I see one!" This is an in-joke: Sock is played by Tyler Labine and Kendall is played by his brother, Kyle Labine.
At the hospital, Sock suggests checking out the 'candy stripers'. In the 1940s nationwide programs started using teenage girls as unpaid volunteers in hospitals to assist nurses. Traditionally they wore red and white striped pinnafore dresses. Since the 70s the distinctive outfits have gone out of fashion, and even the use of teenage girl volunteers has declined.