“I had a 2x4 last night, if you know what I mean. . .”
A 2x4 is a medium sized choice cut of wood that is very lightweight and is usually sold in eight foot long sections. These are not very useful, as an excessively long 2x4 is difficult to hit people with and not very easy to carry. 3' is usually considered the perfect length of a 2x4, although some people prefer a slightly longer piece in order to get a quick jab in when the opponent thinks they are still out of range.
An 8' section can be cut into two 3' sections with a power tool such as an electric butter knife. If cut incorrectly (a common mistake), a 2' section might be left over. This left over piece makes a great door stop. It can also be duct tapeed to the leg of a wobbly table to permanently fix the wobble. If a more effective weapon is required, the left over piece can be nailed back to the the 3' section, although in Scotland the nails alone are more usually used.
2x4s are primarily for hitting people with. This is usually done after the person has done something insanely stupid, like telling their root password to a channel on IRC. At least 1 internet forum actively employs a 2x4 as an initiation ritual of sorts for new users. Some moderators also prefer to use a 2x4 instead of the more popular banhammer.
The Indians first created the 16' long 2x4 for peace pipes. It was first created by carving Iron wood out to measure 16.2 furlong newton squares by 4500 Square Bushel Metrons. Over the years, the furlong newton square and the square bushel metron has been depreciated in favour of the inch. After converting the units of measurement from furlong newton squares and square bushel metrons we arrive at the now popular 16' 2X4. Today, Iron Wood has been replaced with softer wood. This is because the French have made Karat Stones extinct - The only known substance able to cut through the versetile Iron Wood.