Police in southern Poland say they are investigating four English-speaking tourists spotted in the historic city of Krakow wearing only mankinis.

The four men were caught on CCTV and by an Associated Press photographer one Friday as they walked in the picturesque Renaissance Market Square and got into a horse cab. They were wearing lime green mankinis, as worn by Borat, the fictional Kazakh alter ego of comic actor Sacha Baron Cohen.

Krakow province police spokesman Sebastian Glen said police are investigating the “indecent antics.” If convicted, the men could face up to 30 days in custody or fines of 5,000 zlotys ($1,300) each.

Glen said that foreign tourists, especially British ones, who come for stag parties sometimes cause disturbance in the historic city, especially after drinking alcohol.

But apparently it’s a graditional thing to do. Binge drinking is a medieval sport in Krakow.