There was a "toga" night on Explorer, but they did provide the toga's, but go early, we went to get some and they were all gone. They handed them out by the pool one day, kind of interesting to see who people wore their toga's :-) Have fun!
Don't remember any type theme nights, there is also 1 semi-formal night as well.
Don't know about the grape juice, by the time we went to get a toga, there were all gone Quite a few cruisers wore them to dinner, what a sight, kind of glad I didn't have one, if you know what I mean.
Wonder why they voted your idea down??? Could be fun I would think :-)