User blog comment:Endless Exceptions/Bad playing friends./@comment-6334158-20130605120048/@comment-3466579-20130605150947

^ This, and: normals may not reward you like ranked games do, but there's no reason to say "screw normals" and play a bad game, e.g. with a champion you have never tried before, not even in coop vs ai games. You're still playing with other people, your mistakes counts towards the whole team performance, you should at least show some respect for the others.

Back to the topic, my humble advice is simple: you don't have control over your randomly picked allies, you don't even know their skills and experience. When you're playing along with a friend, make sure how he/she can play: if he/she's not that good either accept it and don't get mad if he/she does wrong things or don't play at all.