Whats the worst thing you could do in a match?

Not ward at all.

http://img02.deviantart.net/4633/i/2015/061/3/1/gigasupport_by_gigadoodles-d8k685j.png

Chase

as ezreal, ult down mid and steal all the minion kills from ur mid laner

Flash into a wall to escape a gank/failed gank or get dragon/baron.

Once a tower dived me as a and I full rotation him and he dies from tower. His next words in all chat, "I just tower dived a Malzahar..."

I personally think tower diving the mighty cow is much much worse. You can't milk those.

Let a Nasus free farm.

Tower Dive Leona, Annie, Morgana, Lux, basically anyone with a stun or snare. That or smite poorly. It LITERALLY shows jungler's how much your smite will do and the drag's hp, so..

try and fight an illaoi

Dont tower dive an irelia either lol, so many free double kills because of this