Thaipusam is a festival celebrated by Tamil Hindus, particularly in the state of Tamil Nadu. On this day, devotees put themselves under harsh physical tests of endurance. It’s thought that the Lord Murugan will grant the wishes of the devotees who display extraordinary physical feats of endurance. Lord Murugan was able to defeat the demon Soorapadam. As a result, devotees believe that by performing these physical endurance tests, Lord Murugan will be able to defeat any disease that may befall any devotee or his family.

Devotees undergo extremely painful hooks in their backs and hang heavy items from the hooks. Some put skewers through their mouths, tongues, or cheeks. A disinfectant is smeared over the affected area to prevent infection. The greater the pain, the more Lord Murugan will bless the devotee. Here is a video of what it looks like. I’m going to warn you beforehand, that this might be a bit graphic for some viewers:

Thaipusam is also observed by Hindus outside of India. In Malaysia, it is a public holiday. On Thaipusam, there is a procession of drummers and devotees who walk through the streets in a trance. Some devotees chose to shave their heads bald, offer prayers, carry heavy bundles on their head and eat only one meal a day. This ritual is meant to bring the devotee closer to Lord Murugan.

http://www.youtube.com/watch?v=VRfEoiKAeyc