Comedian Jerry Seinfeld was met with a wave of boos Sunday when students at Duke University in North Carolina walked out just before his commencement speech, the latest in a wave of antiwar protests at college graduations across the country this weekend.

Not only was Seinfeld, 70, delivering the speech at the school’s football stadium, but he was also receiving an honorary degree from the school, where his son is enrolled and from which his daughter graduated. As he was being introduced,…