This wonderful quiz, originally from Walter Penney in the August 1969 issue of Word Ways: The Journal of Recreational Linguistics and now presented online by Futility Closet, is as simple as can be: “Below are five groups of English words. Each group appears also in a foreign language. What are the languages?” I got 3 and 5 instantly, 1 and 4 after some thought, and was stumped by 2. I suspect there will be spoilers in the comments [Update: there are definitely spoilers], so if you want to try, you should do so before clicking through to the thread. Thanks, John and Breffni!
Clarification (since some people misunderstood the way it worked): the words are not etymologically connected, they are words that happen to be spelled the same way in English and another language; e.g. (to take a language that isn’t in the quiz), more and my are Russian words (for ‘sea’ and ‘we’ respectively) as well as English ones.