This is an uncomfortable ailment that occurs between the buttock cheeks. This malady is caused by excessive sweat between the cheeks and the friction of them rubbing together leading to a chapped backside. It is often due to a long bike ride on a particularly hot day. Gringo's arse is usually accompanied by Foy smell.
Nah man! Theres no way I'm gannin oot for a walk today, I've got a canny dose of gringo's arse!