This incident has become a topic of casual after-meal gossip.
Tips
history
From Guan Hanqing's Yuan-dynasty qu-song 《斗鹌鹑·女校尉》: 「茶余饭饱邀故友」 — 'after tea and meals, invite old friends.' The Yuan period's teahouse leisure culture is where the phrase took root.
usage
Typically modifies nouns: 茶余饭后的话题/谈资/闲谈 ('after-dinner topic/gossip/chat'). Slightly literary — 饭后 or 闲暇时 would be more casual.