LORELAI: Uh, well, I guess, I could water your lawn, Dwight – sure.
DWIGHT: Boy, that is something. If I would have asked somebody back where I used to live to water my lawn, I would’ve gotten a much more HBO kind of answer.
Home Box Office (HBO), a pay television channel, owned by Warner Bros. Discovery (Gilmore Girls was on the Warner Bros. TV channel, the WB). First launched in 1972, it was the first pay TV network in the US, and the first in the world to begin transmitting via satellite.
HBO, as a channel available to subscribers, was able to broadcast programs without having to edit them to remove adult or objectionable material, and its sister channel Cinemax even broadcast softcore pornography until 2018. Dwight is saying that he would have received a much more adult-oriented answer in his previous neighbourhood (presumably in a city) if he asked someone to water his lawn for a few days.
Lorelai has always been shown to be pretty good at shutting down anyone who asks her to do anything for them she doesn’t want to, yet somehow, she is unable to resist Dwight’s plea. I guess she doesn’t want to get on the bad side of a new neighbour, or she doesn’t want him to think Stars Hollow isn’t a nice place, when he seems so excited to have moved there. Possibly her fight with Pete, which she later learned she’d been unreasonable about, has taken up all her energy. Or Dwight just has some mystical power over her. Maybe the same mind control that he used to get Beenie Morrison’s house!