The twosome, who once played star crossed lovers Jessie Spano and A.C. Slater in the 90s sitcom, performed an impromptu dance routine as Berkley, 41, visited the show for an interview regarding her "Dancing With The Stars" debut.
Lopez, a "DWTS" veteran, later tweeted a photo of the reunion.
"Tango time with my girl Elizabeth Berkley on Extra TV!" he wrote.
2014: The Year in Music [PHOTOS]