Multimeter experiment with 10A setting -- what happened?
In order to measure current, your measurement device must have that current flowing through it. In order to do this without disrupting the behavior of the circuit, the resistance of the measurement device must be very low. 

Therefore, consider what happens when you put a multimeter set to current measurement mode in parallel with a device hooked up to a voltage source. Because the multimeter has a very small resistance (much less than 1 Ohm), whatever current the voltage source can supply will go through your multimeter, while none will go through the lamp. Note that this current is not typically the normal operating current of the lamp, and is usually much higher, and potentially out of spec for both your meter and the power supply. Therefore, you run the risk of destroying your power supply or destroying your multimeter (or at least blowing a fuse in either).

The proper way to measure current is always in series with your load. For example, in the following circuit, you must break the existing connection to the load to properly insert your multimeter and find the current labeled 'i?'.







simulate this circuit &ndash; Schematic created using CircuitLab