Clientside Bugs, resulting in Leaverbusted and queue times.
- Leaving a custom game, regardless of how many players are in it, counts as a leave for Leaverbuster.
// Tried to learn new champs with my friend the other day, and we decided fighting 1v1 in a custom game would be the easiest way to go about that. After 3 kills or a tower, we would simply leave the game and reset it so we could keep playing. After leaving 2 games this way however, I was put in a 5 minute leaverbuster queue for 5 games. Goodbye casual theorycrafting. 
- Wait times for client bugs
// Client bugged out in lobby, left me and my friend hanging with a "getting data from server" box. We waited a couple minutes then i just clicked cancel. It closed the client and put me in a waiting queue for leaving a ranked game and took away my lp.