The 61-year-old actor was joined by wife Amal, 44, on CBS Mornings on Wednesday (September 28), to promote their new awards show, the Clooney Foundation, for Justice's inaugural Albie Awards.
When host Gayle King asked what “delights” their children at that age, the actor quipped: “We made a terrible mistake. We taught them Italian... but we don't speak Italian.
“We’ve armed them with a language they can harm us with, and we don't really know what they're saying,” he admitted, adding that the siblings also speak French.
The Oceans 11 star also joked that, because he's from Kentucky, “English is my second language”.
Amal chuckled, before turning to her husband and saying: “Our son is now a big prankster. You’ve taught him all of these lessons and now he's pranking his dad back.”
Clooney added that little Alexander's favorite superhero is Batman, but he still isn't impressed that his father once played the Caped Crusader.
“I go, ‘You know, I was Batman?’” and he goes, “’Yeah, but not any more.’”
Clooney was in Los Angeles earlier this month, for the launch of the Roybal School of Film and Television Production, where he also joked about his twins being smarter than him.
“They can do whatever they want,” he told the audience. “My guess is that they're a little smarter than me, so they'll probably do something - they already speak three languages, so I'm still working on English.”