Funny, because i actually have had ribs AND corn on the cobb on a first date... it was huge beef ribs too. Girl took me to a family picnic, and that's what her mother made.
As for me, it would probably be crab legs. I did it once, and it was just too messy. When i eat crab legs at home, i sometimes get so fed up with the shell cracker that i just bite the shell apart... and well, doing that in public, especially for a first date, isn't the best first impression.
BTW, we have a Love and Relationship forum now as well.