Kashi Yatra rituals are comical and interesting where the groom gets a chance to escape matrimony by deciding to walk out of the marriage and take up sanyasa (sanyasa is a stage where an individual lets go of everything in the material life and accepts spiritual path to be his way of life).  

The Kashi Yatra Ritual in Tamil Brahmin Iyengar Weddings
The groom pretends to become an ascetic, sage and scholar. This is a small act, enacted by the bride's family and the groom. The groom proclaims that he wants to take on spiritual life and starts off for Kashi, a place famous for spiritual and religious attainment. The groom starts for Kashi with footwear, coconut, rice, spare dhoti, walking stick, an umbrella, but the bride's father persuades the groom to let go of this thought and marry his daughter. Usually, this ceremony is held before the Muhurtham, and this is a hilarious ritual where a merry chase between the groom and the bride’s family is witnessed and enjoyed by everyone. The groom is brought back to the mandap to start the life of Grihastha (family man).

The Significance
The significance of Kashi Yatra details in Tamil is for the groom to understand that he has to move from the stage of Brahmacharya (Bachelorhood) to Grihastha (Family man) and not directly to Vanaprastha (one who gives up worldly things) and Sanyasa (seeking spirituality).  

The Kashi Yatra ceremony adds a spark to the wedding due to the fun involved, yet has a deep meaning attached to it!