Two Drunks – Level 3

Two drunks were in a bar partying like fools. They were drinking whisky, buying rounds like there was no tomorrow. They were dancing, calling each other “professor“, and generally attracting a lot of attention. When asked why they were having such a celebration, they said proudly that they’ve just finished a jigsaw puzzle and it only took them 2 months! “Two months?!” cried the bartender. “That’s ridiculous. It shouldn’t take that long!”
“Oh, yeah?” says one drunk. “The box said 2-4 years!”