I came across this article on Sikh Philosophy Network forum. It is very informative and helps explain the significance of the Kachhera (special undergarment, which one of the 5K's). Sometimes at camps, talks and forums youngsters have questions about the Kachhera and it's significance. The article below helps to explain the significance of the Kachhera:
Author: Hai Bhi Sach
The Kachhera is also known as a “Rave Kachhera” or “Barekaa(n) Waala Kachhera”. The name “Rave Kachhera” comes from the fact that the cloth it is turned diagonally (i.e. at 45 degrees to the direction it has been woven) and sewn together to form a tube which is then further shaped. Hence the word Rave (diagonal). The name “Barekaa(n) Waala Kachhera” comes from the fact that unlike a conventional boxer short, which does not necessarily keep your modesty when you sit down on your feet. Whereas the “Barekaa(n) Waala Kachhera”, because the way it is cut and sewn together, it clings to your thighs as if it has put the breaks on hence giving the wearer a dignified appearance. The leg opening closes up tight against the thighs.
Why invent the special Kachhera for the Sikhs? In fact the kachhera predates Guru Gobind Singh Sahib. The main reason for the existence of this particular design is that during the times of our Gurus the “Sikh Warrior” had to be ready for battle at all times (Tyaar bar Tyaaar). The Sikh warrior did not have the time to change clothes if attacked at any hour of the day or night. The Kachhera allowed the Sikh warrior to operate in combat freely and without any hindrance or restriction. Sikhs fought many battles only wearing this undergarment. The Kachera thus plays a very important part in Sikhs daily life. A Sikh Warrior is always ready to go into action. The Kachhera is thus an important part of a Sikh attire.