xkcd.WTF!?

Explanation ➲

The flowchart shows a problem Randall has with using alarms built into phones. Notably, that the sound is similar to a normal ring tone (probably related to 479: Tones), making it sound like someone is calling him, and not waking him up. This results in him having a false awakening, where he dreams about answering the phone, talking, and eventually hanging up. Of course this doesn't stop the actual phone from ringing, and he ends up answering the phone again. The looping arrow around the "beep beep" box implies that the phone keeps ringing only until he attempts to answer it, which would be quite a coincidence. This is an example of an endless loop, where there is no given way for the flowchart to end, just as in 1195: Flowchart. Now, smartphones typically support customization of tones for different apps so that your alarm doesn't have to sound like your ringtone and many apps load their own distinctive tone now by default.

The title text, consisting of Randall shouting at the phone in his dream, enforces the fact that he can't tell between his ringtone and his alarm. In doing so he believes that a prank caller is harassing him which infuriates him. Alternatively, "the worst person in the world" could just refer to the confused logic in dreams, where a caller could, inexplicably yet unquestionably, be the worst person in the world.

A list of all the flowchart comics can be found here.