What kind of friend? just a friend? or a male friend that I like.... I might play along if I like him.
Pink silk knickers.
he is fapping while talking to you
I would know where this is going.
I usually just ask them why. I'm not really into phone sex.
"OMG I'm talking to a pervert." Or "I'm really not in the mood for phone sex." Or "Wow, He really needs to go get laid."