Ask him/her about life during the Cuban missile crisis.

My father is 78 (and my mother would have been 77 if she was still alive) and I was born on the day Robert Kennedy was assasinated.

1968 was an incredibly volitile year ... 5 years after the assasination of John F Kennedy, Robert Kennedy was assasinated and Martin Luther King was assasinated the same year... and earlier that year saw the Tet offensive in Vietnam - which signaled the beginning of the loss of the war.

He would have been 22 then - so it would be interesting to know how he perceived those events.

It would also be interesting to hear about his opinions or experience of the counter-culture.

You could ask about daily life when he was young, in the 50s. Things were changing quickly then. Entertainment - TV, movies, radio, music. Did he travel and how was it different? Communication - phone, letters? Depending on the guy, he might have some interesting insights. Edit: Typos, hard to type on mobile tonight.