is planning to send pink knickers to the Sri Ram Sena (Lord Ram's Army), which has also censured unmarried couples planning to spend Valentine's Day together.
The Facebook group was founded in protest after the Sri Ram Sena attacked several women in a pub in Mangalore last month. It now has more than 10,000 male and female members.
The group was started by journalist Nisha Susan who told The Times: "[The group] wasn't a serious thing at first, but now it's becoming something bigger.
"Most of us are just regular people. We decided to give the Sri Ram Sena attention, but not the kind they want."
The group has asked its supporters to send in pink knickers, which it will post to the Sri Ram Sena on Friday.
Pramod Mutalik, who heads Sri Ram Sena, is currently on bail following the attack in which as many as 30 were arrested.
Mutalik says it is "not acceptable" for women to go to bars in India. TV footage of the attacks showed men chasing and beating up women.
As women tried to escape some fell and were kicked by Sri Ram Sena men.
According to The Times the idea came about because the Indian slang for knickers, "chaddi", is also applied to members of the Rashtriya Swayamsevak Sangh, an umbrella nationalist group which includes the SRS.
Susan told the BBC News website it was sending chaddis as they alluded to a prominent Hindu right-wing group whose khaki-shorts-wearing cadres were often derisively called "chaddi wallahs" (chaddi wearers).
Susan said: "We chose pink because it is a frivolous colour."