OP might be dutch. In dutch, nouns that end in the single vowels '–a', '-i', '-o', '-u', '-y' get a "-'s" when forming the plural. The apostrophe is added to k

OP might be dutch. In dutch, nouns that end in the single vowels '–a', '-i', '-o', '-u', '-y' get a "-'s" when forming the plural. The apostrophe is added to keep the long single vowel at the end long. That's why dutch speakers frequently make this mistake.