It’s really important to use the right cut of lumber for the job at hand. We can find an example of using the wrong dimension in this story from WNYT:
AMSTERDAM – Two adults and one juvenile were transported to the hospital Friday night after a large fight, according to Amsterdam police. They say the altercation happened on Green Street and Kimball Street around 6:45 pm. Police say a large group of juveniles and adults were fighting with 2 x 4 boards as weapons.
While a 2 x 4 is imposing, it’s very difficult to get a good grip on it. Why not use a 2 x 2 instead? It’s a lightweight alternative that you can easily wrap your hand around. Don’t forget: take the time to inspect your wood for flaws and knots, especially if you’ll be using it in a visible location —like out on the street in front of your house.