Early Show October 28.

Levi Johnston appeared on CBS’ Early Show Wednesday, where he explained his reasons for spilling unflattering information about the Palin family and said he was keeping some “huge” secrets.

Among other things, Johnston said Palin joked about her son Trig’s Down Syndrome, calling him her “retarded baby.”

“I was just in shock the first time I heard it,” he said, when host Maggie Rodriguez expressed disbelief. He also said Bristol took care of the baby much more than her mother: “Sarah was never home.”