Reader Keith wrote to us with a cautionary tale regarding Nivea men’s “cool” body wash. To Keith’s surprise, the product contains menthol which had an adverse effect when he used it on his body, specifically, his genitals. Much like the old Icy Hot in the the jock strap trick, it made his boys burn. To dispel any doubters, Keith says, “And no I do not have an STD, this is Nivea body wash related.” His letter, inside…