Difficult Puzzle

A man was walking down a street when he sees a blonde couple who looked extremely happy. He goes up to them and asks:

“Why are you guys so happy?”

The couple says “We just finished a puzzle that took us 3 years!”

“3 years!” the man said “It doesn’t take that long to do a puzzle.”

“Oh yes it does” said the couple “It said so right on the side of the box 2 to 3 years…!”