I hate websites that unexpectedly throw noise at me. Usually I keep my PC on mute, because random sudden noise - almost always from ads - pisses me off. But sometimes I want to listen to music on my PC, so I turn off the mute. Then suddenly in the middle of a song I hear some loud voice start demanding that I refinance my mortgage.
Shut the hell up.
And it's not like I can just direct my browser to keep sound off - after all, I go to many sites, like YouTube, where sound is sort of a good thing.
I wish everyone who made websites would keep all sounds OFF until I actively click on something, like a "play" button, where I could reasonably expect there to be a resulting noise.
Also, I hate people who can't keep noises at a consistent level. I hate cranking up the volume to hear one video, only to have the next video drive my speakers into clipping.