17 Item whose slipperiness was the subject of a 2014 Ig Nobel Prize-winning study
By our lazy count, this is the fourth time the Ig Nobel Prizes have appeared in a major crossword puzzle (if there is such a thing as a major crossword puzzle) in an English-language publication. The Week used it in their puzzle on October 19, 2015. The New York Times used it in their puzzle on December 20, 2020. The Wall Street Journal used it in their puzzle January 23, 2021
The Igs have also been an answer on the Jeopardy! TV program eight times or so.
(Thanks to Miriam Bloom for bringing this to our attention.)