I've never heard of vampirism being one of the targets of the JWs. They wouldn't use crosses, though but torture stakes.
"Die, vampire, die!"
"Noooooooo...wait...what's that?
"It's a torture stake.
"What do you mean...torture stake, Helsing? What's that supposed to do?"
"It's supposed to stop you in your tracks, monster! I used to use crosses, but ve converted to Jehovah's Witnesses. Now ve use torture stakes. See...take that, and that!"
"Ouch...stop it, Helsing. Stop it!"
"Ja...dees torture stakes pack holy power!"
"No...they're sharp, Helsing. Did Helga join too?"
"Oh...ja, ja! Ve took ze Bible lessons together."
"Bible lessons?"
"Ja...see, I've got some literature right here? Vould you be interested in ze Bible lessons?"
"I don't know...."
"Ze are free! No cost to to you. Vat do you'n say, eh...eh?"
"Ouch...stop it with ze...I mean the torture stakes! FREE, eh?"
"Ja! FREE! It is ze truth, Count! And ze truth vill make you...."
"FREE! Well, perhaps you're on to something herr Helsing! I can always live by blood transfusions, right?"
"Ummm...ve can talk about it, Count. We can talk about it. And please...call me 'brother Helsing.'"