They competed in the 'butterfly'.
swimmers doing the 'butterfly'
a 'social butterfly'
(..) - What else? She had an object deliberately inserted into her throat. Now, that hasn't been made public yet. We don't know what it means. Was it a butterfly? Yes. A moth. Just like the one we found in Benjamin Raspail's head an hour ago. Why does he place them there, Doctor? (..)1991 The Silence of the Lambs