The feeling of a wistful desire to return in thought or in fact to a former Halo experience or game, to one's past Halo-dedicated and obsessed life where the only thing that mattered was pwning n00bs with friends, or to one's Xbox Live family a.k.a. the long disbanded Halo 2 clan; a sentimental yearning for the happiness that only the Halo franchise brings with its cooperative campaign, hours of multiplayer and the lack of a social life or girlfriend/boyfriend.
Person A: "Dude, Billy has been listening to the Halo soundtrack all week."
Person B: "Yeah, he's been really Halostalgic before Reach comes out."
Normally assumed to be a person who is good at math and has good people skills, since that is all their job consists of. However, most of the time in society, cashiers are very impatient people who tend to hate their job and hate the customer they are taking money from even more.
Person A: "Man, that guy was a real jerk."
Person B: "Yeah, he's a cashier."