hindsight? 后見之明, 事后聰明
　　
Being able to see has already happened; as contrasted with being able to see what will happen in the future. (HUMOROUS, USUALLY SARCASTIC)
　　
EXAMPLE:
“When my pompous brother-in-law told me all the business mistakes I made last year, I complimented him on his 20/20 hindsight.”