What does it mean the phrase "Ik ben een geile Turk?"?

No, they are not. Turks were the first real big group of guest workers in the seventies after the ones from Spain. Most did not have a wife and family in The Netherlands and grouped together in bars after work and slept in special houses with little room. A lot of them still had no family life after their family could come over and it is said they would have to work hard. Together with their sons mostly left alone and not been raised, also with north African families, (can't punish children in Holland) it is obvious a person from Turkey is a typical bystander in isolation and not speaking the language or being understood really well... A horny Turk is somehow shocking in social way of thinking.