Does anybody know why these names were selected for Capybara and Cucumber? Or were they just picked randomly?
Cucumber was written by Aslak Hellesøy and named by his fiancee. He asked her for a "catchy, non-geeky sounding name" to replace its provisional name, "Stories".
The name Capybara appears to be a play on "webrat", the name of a similar library which predated Capybara. (An actual capybara is a large rodent native to South America, not really a "rat" but related.)