When celebrities, actors and the like appear on talk shows and recount an embarrassing story from their childhood, it's quite rare to have said family members in the audience as it's told.

Mostly, these stories are pretty benign and not all that interesting, but James McAvoy doesn't go for that. As he explained on 'Graham Norton', McAvoy's go-to story about childhood embarrassment involves his granddad's razor, his balls and shaving them at the age of about 12.

That's a funny enough story on its own, but throw in the fact that James McAvoy's actual granddad was in the audience when it happened and it's... well, their faces tell a story that few else can make sense of.

Here's the clip.