Little boys and their dirty words

Molly, my third grader approaches tentatively with a pained look on her little face.

She whispers that Sam has said a bad word about a girl's body part, but refuses to even utter the word.

Of course, I need to call over Sam and ask about the word. He hesitantly admits that he's said this word.

What word?

"The B word."

Hmmm, I wonder, I try to think what it possibly could be.

Finally, I say, almost pleadingly "Sam, just tell me what the word is." 

"Um, um, um - you know..... Bagina."

Note to self: Review phonics instruction.