The president drew some boos for his joke about the trade of Boston infielder Kevin Youkilis to the Chicago White Sox over the weekend.
"Thank you for Youkilis," the president said. "I'm just saying, he's going to have to change the color of his socks."
Mr. Obama is well-known White Sox fan.
Youkilis, a Red Sox fan favorite, played with Boston for eight years. He was also part of two championship teams.
The Red Sox traded him for utilityman Brent Lillibridge and right-hander Zach Stewart.