you hit find match with positive mentality "I am gonna win games in a row" sorta mentality you get into camp. select and there is some idiot who wants to play Soraka jg or full ap Ashe top or something stupid like that, you think to your self oh go here we go again you try to be nice and ask them to pick a decent champion that fits their role and sometimes it works and the respond.
but most of the times you either get absolute silence as if they're telling you to STFU from behind the screen or they would tell you to chill because they're the best Soraka jg the world have ever seen.
now you have to decide I'll play and see what happen and in this case you're probably gonna waste like 30 minutes of your life, or you just dodge the game and save your self the struggle it's only 5 minutes punishment after all.
you get into champ. select again and what do you know another idiot wants to play full crit adc Kat and yes you guessed it they're "the best full crit adc Kat the world has ever seen"
eventually you get placed in low priority q for being an asshole and destroying the game experience for your nice team mates.