My informant is my 74 year old grandmother, who is a language professor born and raised in Mexico City, and currently living and working there. She heard of this folk remedy from her mother when they would go to Veracruz (her mother’s hometown), because the climate there is very hot and tropical and mosquitoes are a big problem. She likes it because it’s useful and reminds her of Veracruz and her older relatives, and she can pass it on to the younger generations as a useful thing.
The folk remedy is for mosquito bites, and consists of tobacco and rubbing alcohol. You’re supposed to steep the tobacco for a bit in the alcohol and then rub the combination gently on a mosquito bite; she’s done this for as long as she can remember and always reminds us to do the same.