A “ladyfinger” is a type of long, thin cookie. He needs a larger ring because she doesn’t have arms or digits, so as the title panel explicitly states, she’ll be wearing it as a belt around her whole body.
Made of sponge cake, encrusted with sugar . . .
The secondary joke reminds me of Alice’s confusion as to whether Humpty was wearing a belt or a tie.
Comics I Don't Understand 
A “ladyfinger” is a type of long, thin cookie. He needs a larger ring because she doesn’t have arms or digits, so as the title panel explicitly states, she’ll be wearing it as a belt around her whole body.
Made of sponge cake, encrusted with sugar . . .
The secondary joke reminds me of Alice’s confusion as to whether Humpty was wearing a belt or a tie.