He was depicted as a fat-cat landlord stuffed full from idle living.
Tips
history
Recorded in the 北齐书 ('Book of Northern Qi, Biography of Prince Yan of Langye'): 琅邪王年少,肠肥脑满,轻为举措, describing the young prince as 'pot-bellied and fat-headed, careless in his decisions.' The original word order was 肠肥脑满; the modern form swapped them.
register
Always derogatory and vivid, used to mock the rich-and-idle, corrupt officials, or oppressive landlords. Strong enough that you wouldn't apply it to a friend; literary register, common in op-ed writing and political satire.