Yep four words the whole world knows. F.u.C.K, amen, coke cola! All english. Never been anywhere everyone didn't understand these words!
Actually, all are examples of words whose origin is not English.
That is of course one of the great features of the English language - it takes up words, plays around with them, and over time even changes the meaning, and sometimes the pronunciation and spelling of them. Words are allowed quite free rein, unlike some other languages.
That is why dictionaries are so useful, but need constant updating. They don't prescribe the words we can use, and how we may use them. They serve instead to describe them - and it can be a job for the lexicographers to keep up.
