The boss treated everyone to a meal out of his own pocket.
Tips
memory
Picture it literally: 自 (self) + 掏 (dig out) + 腰包 (waist pouch / wallet) — 'dig money out of your own waist pouch'. The image is the old-style coin pouch worn at the waist.
usage
Often implies that someone covered an expense they were not strictly obliged to — used both with admiration (generosity) and complaint (no reimbursement).
