What is Rum Raisin?
1.
Something that is better than nothing, but not the exact thing that you would choose if you had a choice.
If you are eating rum raisin ice cream, you are at least eating ice cream and that's pretty good, but if it were up to you there are about 5000 other choices of ice cream flavors that you would prefer instead of rum raisin.
Bob: How did you like the movie Bruno ?
Chris: It was pretty "rum raisin" when compared to Borat.
See