Fifty-five!

Two men were sitting at a bar one day. They ordered their drinks and sat at the bar for a while. Suddenly, they both stood up, slapped hands, and yelled, "Fifty-five!" The bartender was pretty confused but just decided to ignore them.

About five or ten minutes later, they both stood up again, slapped hands, and yelled, "Fifty-five!" Again the bartender just decided to ignore them.

Ten minutes later they followed the same routine. By now the bartender was getting pretty annoyed, so he went over and asked, "Why do you guys keep standing up and yelling fifty-five?"

One of them said, "Well, today after work we decided to work on a puzzle. On the side of the box it said 2 to 4 years, but we got it done in fifty-five minutes!"