Potresujka is a form of polka danced in rural areas along the Kværner Bay in Croatia and up to the Slovene border. The difference between potresujka and regular polka is that one changes foot position only on the heavy first beat of a measure, then bounces twice using the balls of the feet. The body remains erect and stiff the whole time, giving somewhat the impression of dancing mechanical toys.
The municipality of Matulji has recently been quite active in promoting and teaching potresujka through evening courses. I visited one of the courses yesterday, finding about 50 dancers of all ages trying to learn the basic step - which is not nearly as easy as it might sound!
Although it has been danced locally for several generations, potresujka became known over all of Croatia in 2004, when a song about it was performed during the MIK festival in Opatija. The wide popularity of the song had an immediate effect on the local population as well as on the media charts, since many people suddenly wanted to become proficient in the dance that was considered characteristic for their area.