LORELAI: Luke, um, that’s not a bed, that’s a raft, which is fine if you’re gonna build a moat around the diner but …
LUKE: It’s fine.
LORELAI: Luke, the kid needs a bed. If you want to get him something inflatable, make it a blonde.
Lorelai is humorously referring to inflatable sex dolls. She also refers to the blow-up mattress as a “raft”, which feels like another subtle nod to Huckleberry Finn.
During the show, the (dark-haired) showrunners had a habit of making blonde women the butt of their jokes, and blonde characters were usually shallow, stupid, spiteful, or all three. There’s a slight suggestion here that blonde women are little more than sex dolls (otherwise, why does the sex doll have to be blonde? They could have any colour hair).