Some families talk about a lot of different things, while others don't. If you're in the latter, consider asking your dad these questions about his life this Father's Day. Better yet, write them down so you'll always remember the unique details of his life.
This question provides a prompt for your father to talk about his views on life. You'll learn a lot by his answer, like why he hounds you on certain things, the life lessons he's endured but never told you, or the things he might have done differently.
This is also a subtle way of finding out what the relationship with his own father was like. Did he get along with his own father? Was your grandfather affectionate? Distant?