My favorite thing to do is mock the songs while I am singing them by inserting alternate words or clearly pronouncing the rediculously shortened words such as "pow'r" and "heav'n".
...From house to house, from door to door, Jehovah's turd we spread. From town to town and farm to farm, Jehovahs sheep are bled...
...Then forward, you Witnesses, ever wrong of heart! Rejoice that in God's work you too may have to fart!
Just soften the consonants and they'll never hear it...
...Live for the day when you'll say: "Life without end, I'll pass!"
My favorite line of all the songs: "We will not be de-terred." You got that right.