My speaker was Ted Sorensen, the adviser and speechwriter in JFK's inner circle.
He was very elderly and rather incoherent during his speech, and rambled on and on about obscure political issues and was bashing George Bush. It got to the point where much of the crowd was visibly and audibly restless, and the whole situation was becoming more and more awkward. The Dean had to take over the mic and tell everyone to settle down and show proper respect.
My conservative grandfather did not take kindly to Sorensen's speech, and at one point shouted out, "This is a graduation ceremony, you a$$hole!" He passed away a few years ago and our family still cracks up about that.