1. The buttock(s). In this sense the word is common in Australia, normally in the singular form.

2. The testicle(s). Usually in the plural, this sense of the word is typically used by British schoolboys. 'I told the estate agent I couldn't afford any land, so he kicked me in the balls and said, "There's a couple of achers for you".'(Schoolboy joke, London, 1965) Both senses of both words stem from the simple play on the word 'ache' which has formed part of many different puns and dirty jokes during the last forty years, in- volving sensitive parts of the (male) anatomy.