Im assuming as the OP is asking the following question chances are hes not to sure what ssh is... but if he has an andriod or jailbroken iphone then learn how to ssh and you can get into his phone over wifi ssh and terminal and go tru his folders. if hes at home i reakon he would be on wifi so you would first need to get his phone install ssh get his LAN ip address and off you go.

My advice also would be if hes 16 and over let him watch his pron or look at xxx pics its part of life why stop him? unless your family is really religous or somthing.