I don’t know. You want the wedding to be memorable, right? 
I totally misread the thread title. My brain interpreted it as saying…What are some deal breakers for wedding tables. The only one I could come up with was “if it is broken.”
How about if somebody took a shit on it?
I worked in catering for a couple years. Trust me, we can do wonders with the right tablecloth.
I tried to google the name and couldn’t find it so I must be really off. A game called Ad Libs? They’re sort of funny and maybe someone could make one up relating to weddings for each table.
Cardiwen,
I think you mean Mad Libs.
Ditto.
What you are supposed to do is spread the family around. You know, put one couple at each table that you need people spoken to or whatever. And it’s their job to keep the conversation up.
Thanks! 
Surprised they got married? Hell I didn’t even know she was pregnant.
Well there is always the pull my finger routine.
No, THIS is the best icebreaker.
The last wedding I went to (last Mayish, I think) the not-so-very-blushing bride passed out naked pictures of the not-so-Maidish of Honor’s daughter.
It seems the daughter was last years Penthouse Pet of the year. In case you were wondering.
It is still getting conversations started.
Yes, but I think the point is the awkwardness gives everybody something in common. Everyone thinks, “Oh, not this…” BAM…instant conversation starter. “Jesus…I hate this crap.” “Yeah, so do I.” 
I was coming in to suggest this. It was a great icebreaker, and netted us some fantastic photos.
A bucket full of tinkertoys or Legos.