Most automated phone systems.

Everybody has had to call tech support on one occasion or another.  So most people are aware of the modern 'convenience' that is automated phone systems.  But it would be rude for me to clump them all into one category.  There are the touch tone systems which rely on you pressing certain buttons to navigate through endless menus, and there are voice-activated systems.  The touch tone systems often have a female voice list off options, followed by the number to select them.  By the time she's done saying the options, you're bound to forget which option you wanted to choose.  The voice-activated systems can be just as confusing though.  The worst sometimes go like this:

System: "Thank you for calling technical support!  You can use short phrases such as 'I need help sending a text message', to answer the following question.  What are you calling about today?"

Me: "My phone needs to be activated."

System: "So you need help with My Verizon?"

Me: "No."

System: "What are you calling about today?"

Me: *Click*.

Pro tip: A lot of systems actually do have the ability to transfer you directly to a human if you press 0.