It was my 3rd year at the company, never was sick/on sick leave, but that time I got acute flu and decided to stay at home. We could be on sick leave for 3 days without providing a medical document. On the 2nd day around ~16:00 I got a call requesting a certificate. I don't think it's possible to get an appointment with doctor in 2 hours and I also had headache and said that I'll better take a vacation day. I still don't know why the hell was that needed.