Jamala, victor of last year's Eurovision Song Contest who took the crown for Ukraine, was joined on stage by an uninvited guest during her performance at this year's concert.
Saturday's Eurovison contest was won by Salvador Sabral of Portugal.
The singer maintained her composure and continued her song as security dragged him off the stage.
The prankster sneaked on to the stage pulled down his shorts and wiggled his bum at the cameras during the eight-second escapade.
It was the moment Jamala, the 2016 Eurovision Song Contest victor, was expecting the whole year after her victory in Stockholm.
Some experts are wondering if a mooning reveller with an Australian flag hampered Isaiah Firebrace's chance at Eurovision victory after Australia came ninth.
"During the performance of our Jamala, according to his own words, he chose to realise his hobby as he "unofficially works as a provocative journalist", Mr Avakov said.
Earlier, Graham paid tribute to former Eurovision host Terry Wogan, urging viewers to toast the "late, great" Sir Terry Wogan.
Eurovision was hit by an unexpected streaker during this year's interval performance.