Finger Licking Lichen?

People in New Zealand have been warned not to consume 'sexy pavement lichen' in spite of its being claimed by some folk to act as a natural alternative to Viagra (https://www.theguardian.com/world/2019/aug/15/new-zealanders-warned-about-the-consumption-of-sexy-pavement-lichen). Firstly, there are doubts about its sexual benefits and, secondly, the fungus is likely to be contaminated with urine, dog faeces and pollutants from road traffic. Licking it could make consumers seriously ill rather than converting them to 'sex machines'.