The Desperate Housewives star is on a tour of the U.K. to promote the upcoming relaunch of legendary drama series Dallas, in which he plays Bobby Ewing's adopted son Christopher.
But he left the audience of chat show Loose Women stunned when he tried explaining the relationship with his character's cousin John Ross Ewing, played by Josh Henderson.
Metcalfe said, "The two cousins are coming from very different places. They are very much like their fathers in a lot of ways. John Ross is very much like J.R., in the sense that he's a very unscrupulous, you know, little b**tard, basically."
The remark drew gasps and laughs from the panel, prompting co-host Carol Vorderman to tell viewers, "Apologies for that."