is a series of humans disguised as a sex robot

First, you follow The Sext Exchange, and then you wait for it to follow you back. When you direct-message it something that starts with "sext:", it'll send you something that starts with "sext:" in return. Later, it'll send your sext (anonymously) to someone else. This will continue happening until everyone involved gets very tired.

The Sext Exchange listens to some other commands via DM, such as flag, which will mark the last thing you got as needing investigation and will automatically prevent you from receiving any more messages created by that person. You can vote up a sext by replying with yes or ;), or vote it down with no or :(. Spam or hate speech, of course, will get you permanently ejected from the sexting parlor.

More questions? My friend and yours (and noted sextpert) @endoftheshow has very kindly written you

the FAQ

recently sexted

someone sent thisand got this back
Sext: still so bored and horny.
sext: I know a fun game ;D
Sext: I'd make my kitten purr like there's no tomorrow
Sext: my dick is Rock hard
❣ means the recipient liked this sext!