As long as people don't spam the same answer each time, I think it would be fine to allow ping-ponging in this game. It's similar to The Two Above Shipping game, What Do The Two Above Have in Common game, etc. in that regard. If two people are on a short roll, no need to hinder them. (with "short" being less than 15 posts, going by the general F&G rule regarding limited ping-ponging.)