Ozzy Osbourne is a big enough rock legend that he can have Robert Plant’s phone number in his cellphone. However, that can lead to some awkward incidents, as Jack Osbourne revealed that he accidentally texted Plant to say that he had lost the cat.

The father-and-son team were on Conan to promote their television show Ozzy and Jack’s World Detour. The clip above finds them discussing the difficulties of driving long distances with Ozzy, which ranged from his refusal to roll down the windows after passing gas to his poor skills as a navigator.

It was the latter that intrigued Conan O’Brien, and he brought up the idea of map-reading being outdated in the era of having GPS on your smartphone, at which point we learned that Ozzy is inept at using his. “He once accidentally sent Robert Plant a text message being like, ‘I can’t find the cat,’” Jack said.

After the laughter died down, O’Brien envisioned the scenario on the receiving end of the text. “I love Robert Plant in concert singing a Led Zeppelin tune and getting a text from Ozzy,” he said. “‘Buy more milk.’”

So how did Plant respond? According to Ozzy, “He sent it back going, ‘You can’t find the cat?’”

Ozzy and Jack’s World Detour premiered on the History Channel over the summer and sees the two men visiting famous sites around the world, ranging from Stonehenge to Sun Studios in Memphis. “[It’s] like a father and son spoof on history,” Ozzy said when the show was announced. “History with an Osbourne slant.”

A Complete Guide to Black Sabbath Lineup Changes