LORELAI: Dwight says it needs it now, and if we let that lawn die, he’s gonna vibe us for the rest of our lives.
Vibe, short for “vibration”. Slang meaning the atmosphere or aura felt belonging to a place, person, or object, often made specific as “good vibes” or “bad vibes”. Originally New Age jargon from the 1960s.
Lorelai seems to fear that if Dwight’s lawn dies, he will give Lorelai “bad vibes” forever. Dwight doesn’t actually seem the type to do that, but nobody wants to kill their new neighbour’s lawn.