"As Ti… how do you say it?" Garth quipped, prompting Spelling, 43, to jump in, saying, "Just say, 'That which we don't speak of.’”
The pair laughed at the joke as the contestant looked shocked, and Garth said, "Yes, we know her as 'That which we don't speak of.'"
After getting off to a rocky start on 90210
, Thiessen told Howard Stern
in 2012 that she and Garth became “very good friends.” But they once again had a rift later in life.
"We had a falling out and we grew apart," Thiessen said at the time. "I was the one who was hurt, let's just say that."
Thiessen also revealed that Spelling’s 2005 split from her first husband when she met current husband Dean McDermott led to the end of their friendship.