Imagine this... you're a lesbian, and you're doing it with your cannibal girlfriend. You say, "Eat me, baby!"
She pulls out a knife and fork.
Alright listen up, genius. The joke here is that one lesbian is a cannibal. The other lesbian says "eat me," meaning sexually. But the cannibal hears it literally and gets out the utensils to eat her. You probably use a spoon to eat cereal so I had to dumb it down.