The A-word

Ankit: There is anohter way to say donkey that adds a bad word to it

Mummy: What?

Ankit: The word is jackass. Jack and the 'a-word'
(brief pause)
Ankit: Why do they call it the "a-word". What if there is more than one bad words that starts with 'a'. Then what do you call them.

Mummy: (quiet, wondering how to distract the kid from this topic)

Ankit: Also is there any "th word"

Mummy (in a desperate attempt to distract): Ankit, do you know what is 20% of 50?