College football teams are holding their spring practice this month, and most of them end the two weeks of practice with a scrimmage game . . . offense against defense.The  Nebraska Cornhuskers had theirs on Saturday in front of 60,000 fans . . . and the highlight was when a seven-year-old kid named Jack Hoffman got to come onto the field. Jack had a golf-ball-sized tumor removed in 2011 . . . and he's still undergoing treatment for cancer.  He became friends with some of the Nebraska players while undergoing 60 weeks of chemotherapy. So the team invited Jack to run a play in their spring game.  They called a play . . . the quarterback handed him the ball . . . and Jack ran 69 yards for a touchdown.