I hope no one listens to that old timer you know.......all the science I have read specifically states you can not increase immunity from poison ivy/oak but the opposite happens it eventually actually breaks down your immunity ......ive seen people burn it and end up hospitalized from the smoke exposure ....on the flip side ive watched cattle eat it like candy. I have always seen oldtimers use the jewel weed google it if you dontknow what it is ......in my opinion its a bushcraft instant plan but the only way to flat out not get it is to wash away the oil it leaves on your skin/ clothes with cold water and strong detergent soap.........hot water can open your poors and make you more prone to outbreak