Here's why you need an adapter
The outlets and plugs used in Nigeria are D & G. Take a look at the pictures below to see what each plug and socket type looks like.
Voltage and frequency American Samoa vs Nigeria
All outlets in American Samoa provide a standard voltage of 120V with a frequency of 60Hz.Voltage: 120V Frequency: 60Hz
All outlets in Nigeria provide a standard voltage of 230V with a frequency of 50Hz.Voltage: 230V Frequency: 50Hz