Have a double wedding?
HELL NO! That sounds like the worst idea ever.
ETA: I'd avoid this arrangement because it is way too complicated to plan for 4 groups of friends/family, and I don't think I am generous enough to share me and hubby's "special day" with another couple.
Incorporate pets into your wedding?
Yes... because I think of them as humans.
Have a theme wedding (ie Renaissance, gothic, Star Trek)?
What are some other tacky wedding ideas?