First off: the video below is Mostly Safe For Work. You really don’t see “anything”, but it’s not for want of slowing down the video, squinting and watching it repeatedly. Not much detail on what is happening here, but it appears she’s a fan of the Dynamo Kiev team whose male fans have a tradition of taking off their shirts and bouncing up and down in the stands. This young lady decided to join along and, except for a strategically places team scarf, this would be an R-rated video you wouldn’t be seeing here.
With the scarf, well, you just have to use your imagination. Does this ever happen at American football games?