The word avocado comes from the Spanish aguacate, which derives from the Nahuatl (Mexican) word āhuacatl, which goes back to the proto-Aztecan *pa:wa. In Molina's Nahuatl dictionary "auacatl" is given also as the translation for compañón "testicle", and this has been taken up in popular culture where a frequent claim is that testicle was the word's original meaning. This is not the case, as the original meaning can be reconstructed rather as "avocado" – rather the word seems to have been used in Nahuatl as a euphemism for "testicle".

Source: Wikipedia