A traditional "nalangu" function, often seen in South Indian weddings, is a fun and light-hearted ceremony that takes place before the wedding, usually involving the groom (referred to as "mappilai" in Tamil). It's a pre-wedding event where family and friends gather to engage in playful rituals, sing traditional songs, and celebrate the upcoming nuptials. The function is typically informal and filled with laughter, bonding, and some fun activities.

For the groom, the "nalangu" ceremony is often marked by playful teasing, games, and sometimes even a bit of traditional matchmaking-style rituals. The groom might be dressed in a simple or traditional outfit, and various family members may take part in an array of traditional songs, dances, or rituals, such as:

1. **Teasing with the groom**: Relatives, especially the bride's side, may tease the groom by singing playful songs and engaging in fun challenges or games.

2. **Tying of "pattu" or flowers**: The groom might be adorned with flowers or even "pattu" (a type of traditional cloth) as a symbolic gesture of welcoming him into the bride's family.

3. **Smearing with turmeric**: In some villages, turmeric paste is applied to the groom's face and hands as part of the ceremony to bless him and purify him before the wedding.

4. **Dancing and singing traditional songs**: Music is an integral part, with both families participating in song and dance routines, adding to the festive atmosphere.

5. **Sweets and traditional foods**: The celebration often includes delicious local sweets and meals, with everyone enjoying a grand feast after the rituals.

This function is meant to bring everyone closer and adds to the festive mood leading up to the actual wedding day. It also serves as a way for the groom to bond with the bride's family in a relaxed and informal setting.