According to WikiPedia: Toxicodendron radicans, better known as poison ivy (older synonyms are Rhus toxicodendron and Rhus radicans), is a poisonous North American plant that is well known for its production of urushiol, a clear liquid compound found within the sap of the plant that causes an itching rash in most people who touch it. The plant is not a true ivy (Hedera).
When I looked up urushiol, I found the following:
Urushiol is an oily organic allergen found in plants of the family Anacardiaceae, especially Toxicodendron spp. (e.g., poison oak, poison ivy, poison sumac). It causes an allergic skin rash on contact, known as urushiol-induced contact dermatitis. The name comes from the Japanese word urushi, which denotes a lacquer produced in East Asia from the sap of the Toxicodendron vernicifluum (Lacquer Tree). The oxidation and polymerization of urushiol in the tree's sap in the presence of moisture allows it to form a hard lacquer, which is used to produce traditional Chinese and Japanese lacquerwares.
I am sure that you would get quite lacquered if you romped in the nude in the pictured field.