Preston's presents are often unhelpful -- unnecessary, ridiculous or inconvenient. However, he always gives out of the goodness of his heart, so it's hard for other people to get angry with him.
Preston's debut, Episode 2616, is an extended spoof of The Music Man. Preston's clothes and his persistence in giving gifts (rather conning people) spoof the musical's title character, Henry Hill. His name is a take on Robert Preston, the actor who starred in the film version.