James McAvoy shared quite a hysterical story about the first time he shaved “down there.”

He was only a kid when he reached for his grandfather’s razor and decided to give his privates a shave. Turns out, he quit halfway through because “it wasn’t working” for him.

But his parents saw blood on the razor… “Show us your wrists,” James recalls them demanding. “We’ve just seen your granddad’s razor and it’s got blood in it and there’s blood in the toilet. Show us your wrists, son! Show us your wrists!” He finally had to admit, “I was shaving my balls!”

“They were very kind of like, ‘What? What?’” he added. “And it took a while before they gave me the talk about hygiene and how my granddad uses that razor on his face.”

Watch his interview on The Late Show with Stephen Colbert above.