Imagine your friend made the following circuit for an experiment, out of curiosity:
If he connects both the wires to a single terminal of the bulb, the bulb starts glowing as soon as the wires are connected to the cell.
The filament of the bulb is connected to the two terminals of the bulb. When current flows through the filament, it glows.
As the two terminals of the cell are connected to a single terminal of the bulb current would not flow through the filament. This condition is similar to the one in which the bulb is not connected to the circuit at all. Hence, the bulb does not glow. The bulb would have glowed if both the terminals of the bulb were connected to the terminals of the cell.