RORY: Apparently, maturity is extremely overrated in your universe.
LORELAI: That’s right. The Empress Bobo Belle forbids it.
The Empress Bobo Belle is the fictional ruler of the universe, a character that Lorelai has invented and portrays as evidence of her immaturity.
Bobo is a common name for clowns, while Belle is the French word for “beauty”, possibly to suggest “clownish beauty” for the imaginary empress, and how Lorelai may see herself.
The Annotated Gilmore Girls 