I'm going to call out my friend/co-worker for calling in sick
Why would you do that to your friend/co-worker?
He keeps doing it so often, he is clearly lying.
It is reasonable to be angry when other people miss work for lies. People should be truly sick when they call out for sick days.
If a friend is truly sick; I should support his/her decision to be home. There is no place for lies in this friendship.
I agree with you and think you've made the right decision to call out the lies.