Janet Jackson's paying homage to arguably the biggest moment of her career ... 'cause one of her dancers grabbed her chest from behind during her recent show -- and, it's pretty clearly a "Nipplegate" reference.
The singer-songwriter took the stage at Resorts World in Vegas Monday ... and, while outfitted in a tight black leather bodysuit, a dancer came up and ran his hands over Jackson's chest ... while Ms. Jackson looked ready to get 'Nasty' with it.
Jackson's got her hands above her head here .