You can say this with my permission:

"Ron says you can kiss his ass. He says that will all sincerety as a former Full-time Missionary, Bishop, High Counselor, High Priest and Scoutmaster."

Takes the pressure off you. :)

Just sayin'...

Ron

Here's another one:

When they start mindlessly spewing out the Mormon memes just sniff a few times and say, "Woof, woof, bark, bark."

That way you can add to the conversation on the same content level.

Or, here's another one....

Say to them, "When I snap my fingers you will come out of your trance." Then start snapping your fingers. (This one really pisses them off when they start going into testimony or witness mode but it stops them fast.)

I like a good eye roll followed by a distant vacant stare.

Or interrupt them with a sports news tidbit.