I'm going to snoop through my friend's phone
Why are you going through your friends phone?
I want to see his phone log.
Would you want someone snooping on your phone? I think it is not right to look at someone's phone without their permission. It's an invasion of privacy.
Nah, it's fine for me to look at his phone, I deserve to know what my friend is up to.
If you want to know what he is up to, then ask him. Anything he does not tell you is something you do not need to know. Snooping through his phone lets him know he cannot trust you.