We had a great time in Jet and Frank's apartment!
The place is pretty close to the central station so we just walked there. Frank welcomed us to the house and even gave us a ride to the street "witter" for dinner. His recommendation was awesome, we tried some local holland food :)
In the morning, he offered us cappuccino and we bad a great chat.
Just strongly recommend this place to stay, which is perfect for four persons! Can't wait to go back to rotterdam too cause it's a cool and modern place!