A few words about Tantric or Thantric rituals and explaining why it actually nothing to do with sex
The word Tantra is formed by the combination of two words tattva and mantra. Tattva resembles science of cosmic principles while mantra refers to the science of mystic sound. Tantra has its existence in our Indian spiritual studies since past and has a detailed description in the spiritual texts. But till now its considered to be associated for an evil use, people even consider it to be black magic.
If one looks back to its existence in our Indian society, we can trace that its broadly mentioned in the Vedic texts. This is originally an important Indian tradition which is dealt with performing pooja and worshiping deities.
The most favoured deities are Sun, Shiva, Shakti, Vishu and Ganesha. In the ritual performed the god and goddess are worshiped and honoured to please them. For this several shlokas and mantras are also recited.
There are generally 16 principal ritualistic accessories used in the ritual starting from asana(seat), swagata(welcome), Padya(water for washing feet), Arghya(rice, flower, sandal paste), Achamana(sipping water), Madhuparka(honey, ghee, milk, curd), Snana(bathing), Vasana(clothes), Abharana(gems), Gandha(perfume and sandal), Pushpa(flower), Dhupa(incense stick), Deepa(flame), Naivedhya(food) and Namaskar(prayer). These offerings can vary from god to god, but are the often followed ritual.
The key elements of Tantra are mantra and yantra, these two instruments helps to invoke the deity. Some of the ritual also includes some sacrifice to please the deity. The tantric meditates and meditates considering the head as moon, heart as sun and the genital as fire.
Another element of the tantric ritual is the role of sex, the tantric text tells that sex has three distinct and separate purposes — procreation, pleasure and liberation, thus has a unique place in tantric rituals.
Pallivetta (meaning royal hunt) is an important ritual performed on the second last day of the annual temple festival in all temples in Kerala. It is a thantric ritual (besides the normal daily worship rituals to propitiate the deities) - to increase the glory and power of the deities and sometimes in atonement for any act that is might have decreased the power of the deity. The Pallivetta is held on the eve ofAarattu.
During the Pallivetta held in connection with the temple festival at the Padmanabhaswamy temple inThiruvananthapuram, the head of the royal family shoots a tender coconut using a bow and arrow. This ritual is symbolic of Lord Vishnu (the presiding deity of the shrine) hunting down the demon of evil in a forest.
In other temples the ritual would be the cutting up of a vegetable. Crowds of devotees following the deity as it is taken in a colourful procession from the temple and displayed in another location which may or may not be in the temple precincts. Once the rituals are over, it is returned to its place in the temple.
Another explanation for this ritual is that the gods and goddesses are brothers and sisters and one of them is paying the other an annual visit.