Unless you come up with proof no such penis exists. The longest in adult entertainment are maybe half that length. The longest on record is 13 something which is DLD's goal. DLD, Mandingo, Lex Steel are already in the 99.99th percentile on size. A statistical analysis would show a that a true 18 inch penis capable of erections is such an outlier that less than 1 in the number of stars in the universe actually exists.