After you build the Town Hall, accept the mission to collect 50 pieces of Lumber in your Basic Workshop and finish it. When you get the message for completing it, it will be "He's a Lumberjack and he's OK", which is a quote from Monty Python's "Lumberjack Song".
ACHIEVEMENT - HOW TO UNLOCK If I Had a Hammer (5 points) - Build a lumbermill (Single Player). Siegfried (or Roy) (5 points) - Train a Kefling (Single Player). Frank Lloyd (25 points) - Unlock 25 blueprints (Single Player). Big Bully (15 points) - Became the big bully of the village (Single Player). Haberdasher (20 points) - Encounter every possible Kefling hat (Single Player). Like Rabbits (15 points) - Reach a total Kefling population of 30 (Single Player). Think Big (10 points) - Build a building made of more than 8 pieces (Single Player). Master Builder (25 points) - Build a cathedral (Single Player). King (40 points) - Finish a complete castle with three connected parts (Single Player). Friend (10 points) - Collect 10 unique player banners from other giants during Xbox LIVE play. World Traveler (10 points) - Play in an online game where 20 different player banners appear. Vanity (20 points) - Built a glorious statue of oneself (Single Player).