Worst feeling in the game?

Nah losing like 5 games and a row and being demoted for the 5th time between silver 2 and 3 is the worst feeling ever.

Picking ADC and you see the enemy team in loading is

taking blue and and enemy adc gets a double

Used to be packet loss, but that's largely been resolved, for me anyway. Packet loss basically caused you to lose control of your character. No moving, no abilities, no typing, nothing, but it did let you watch helplessly as you got murdered by the enemy team, and your allies report you for intentionally feeding because it kicked in right as you clicked to move forward slightly. Horrible feeling..

Losing a promos game because of an over aggressive jungle. When an entire team is great and works as a unit but the jungler messes it all up...

the feeling that there is nothing you can do to escape and survive versus specific champion *cough cough