knave, nave

Knave or knave means a young man or boy, particularly a naughty or trouble-making young man--
"The knave of hearts, he stole some tarts..."
When she asked the knave if he let the cow into her garden, he ran away without answering.
Knave may also mean the jack in a deck of cards--
A knave is higher than a ten, but lower than a queen.

Nave or nave ( rhymes with knave ) means the central aisle of a church, with the pews on either side--
The nave of the church was decorated with flowers for a wedding.
The congregation didn't even fill the nave of the church.

Now that you know that, you can say--
"The knave let balloons loose in the nave of the church."

Note--"knavery" means  the trouble-making behavior of a knave--
The dean chastised the class for its knavery.
"Knavish" describes trouble -making or foolish behavior, or the person who is making the trouble--
They left  paper streamers in the trees, and committed other knavish acts.
Not to be confused with "navy", the sea-going branch of the armed forces--
He joined the navy to avoid being drafted into the army.