Rhubarb ice cream?
I had a friend who was a science writer. Once for a piece on ice cream that he did, he interviewed one of the Baskin-Robbins developers and one of the questions he asked was "What was the most difficult flavor you've made?" He said it was rhubarb, because there's absolutely nothing in rhubarb that's chemically compatible with anything in ice cream. Basically what they had to do was take the rhubarb apart, remove everything that makes it taste like rhubarb and synthesize the flavor to put back into the pieces of stalk.
So, if it's available at all, it may taste different from other rhubarb ice cream you've had.