My hell would be being forced to stand in front of a crowd of millions on stage, in front of a podium with the spotlight on me and the curtains drawn wide. I will be given the secret of the known universe and the task of present it to all of humanity, and the second I start talking, some chucklehead in the audience yells, "COOL STORY BRO!" And everyone will start laughing.
I will then try and continue, but someone else will start repeating what I say in a mock voice and the laughter will begin again. I will try to stop them, but that will only antagonize them. In a desperate bid for control, I will agree with them and they'll start booing me off the stage for not being entertaining enough for them, and I'll try to give up and leave, but find myself glued to the spot by an unseen force.
As the mocking continues, I will awake as though from a dream...to see myself back at the beginning of the nightmare. This will loop for eternity, and after every attempt to get them to listen to me, I will begin weeping openly as they scream, 'U MAD BRO?'
...on an unrelated note, I'm starting to think I spend too much time on the internet. Hm.