The 81-year-old billionaire is known internationally as the man who described Kim Kardashian, whom he paid US$500,000 (€379,000) for a date, as "boring". He recently announced his engagement to a 24-year-old topless model called Spatzi - real name Cathy Schmitz.
As part of the preparations for the wedding, set for September 13, the couple had ordered a special cake prepared in the Aïda bakery in Lugner's shopping complex, which was put on display for interested shoppers.
On Wednesday morning, an unidentified man - described as having a 'migrant background' - allegedly attacked the wedding cake, snatching the miniature marzipan bride from the top of the cake, and eating it.
An African man was detained by security staff, and may potentially face charges.