My dear Nepalese brother, it is very easy to hate someone or be hated by someone than to love or get loved by someone.
Assuming you have no idea of the history of Indian culture and tradition, i present you here some of the facts about Dhoti.
Dhoti isn't just a thing to make fun of someone you don't like or hate but it has got a very ancient history and deep roots into Hinduism.
Dhoti has a very ancient history in the world and is believed to be a part of Hindu tradition. Dhoti is believed to have existed since even before Tretha Yugam according to Hindu Puranas.
As Dhoti is even today associated with Indian Hindus for traditional purposes, may be it is assumed to be an Indian dress only but it has existed in South Asia and some other parts of the world.
In the present day, Dhoti is generally wore during traditional and other activities like Puja, Yoga, Hindu marriages, Satyanarayana vratham etc.,

One of the great rulers of the world Ashoka chakravarthi was depicted as wearing Dhoti on a stone at Amaravati, India of 1st century BCE.
King Ashoka travelled to Amaravati of South India for spreading of Buddhism. Interestingly, even Gautama Buddha also travelled here to preach his principles very long back before Ashoka did.

Lord Sri Maha Vishnuvu is depicted as wearing a Dhoti since very very ancient times.

Lord Sri Rama, Avatar of Vishnu wore Dhoti in Tretha yugam as explained in Ramayana.

Lord Sri Krishna wore Dhoti in Dwapara Yugam as explained in Mahabharatam and depicted mostly on various architectures of Temples.

Lord Sri Lakshmi Narasimha Swamy, the fourth avatar of Vishnu is depicted as above in various Puranas of Hinduism.

Narada Muni, Vishnu's devotee depicted as wearing a Dhoti in Puranas.

A traditional Dhoti wear in South India is considered one of the most traditional and sacred dress and one of the most ancient in the world.

Members of ISKCON of USA in the New York wearing Dhoti as a part of Sankeertana.
Dhoti is not just restricted to India, it is even getting spread to the western world.