Hot Water in WaterBottle

Usually we used to have a water bottle in office desks. We fill water in the morning. On a Monday morning, i found one of my friends bottle in the pantry and he used to drink only hot water. So i washed that bottle with cold water and filled it completely with hot water and carried to his desk. He thanked me for this activity at start. After few minutes, he felt thirsty and he drank  the water from the bottle. Suddenly he spitted the water on the floor and he started scolding me that Water is too hot.
I didn't realize that the water would be so hot. Even his water bottle would be like a flask not a plastic one.