вдруг(=если случится так, что; напр.: So don't be scared to do less. Be brave enough to stop before you fail and if you do need to go balls to the wall on occasion, choose a safe way in which to do it.4uzhoj)
при случае(There's a big difference. A man who drinks too much on occasion is still the same man as he was sober. An alcoholic, a real alcoholic, is not the same man at all. You can't predict anything about him for sure except that he will be someone you never met before. (Raymond Chandler)ART Vancouver)
время от времени появляться(Stories pop up on occasion of people claiming to be from a different time, like the alleged time traveller John Titor from 2036 and his scary warnings of a civil war in the U.S.ART Vancouver)