In 1963, John Holland answered to ski bum. Sheila Cieszynski Grzebien was known as the “frisky redhead.” Michael Naumoff thought he might become a doctor. They were top teens at Niskayuna High School. Fifty years later, they remember ski trips, dances, stage plays and football games and life inside the classrooms on Balltown Road. John, Sheila, Mike and other “Niska nifties” from the Class of ’63 will gather for 50th anniversary parties this weekend.