An unidentified figure Ferdinand invokes as his benchmark for meanness, unknown to Carl.
Cowering in the ditch in Shanty Town, Ferdinand protested Carl's reassurance by saying 'Juice Box hates me. She's meaner than Bill.'
Carl didn't know who Bill was, nor did he care at that moment. Bill remains unidentified — presumably someone from Ferdinand's life before the dungeon.
Not described.
An offhand reference from Ferdinand's past, used as his yardstick for cruelty.