It's most likely because "get [username]" is the Twitter SMS command to retrieve a list of tweets from [username]: <a href="https://support.twitter.com/articles/14020#" rel="nofollow">https://support.twitter.com/articles/14020#</a> I would wager a guess that you can't tweet "Fav Better" or "Stats Better" either.
It appears the obvious answer may be correct:<p><i>The reason that certain tweet content appears to do nothing is that Twitter is interpreting them as commands, according to this article:</i><p><a href="https://support.twitter.com/articles/14020" rel="nofollow">https://support.twitter.com/articles/14020</a><p><i>The get command will send the latest tweet from the named user to your phone. I've tried some of the other commands listed in that article, and they don't post a tweet. They do, however, have the listed effect. For example, fav accountname does indeed mark the most recent tweet from accountname as a favourite.</i><p><i>It's perhaps useful to remember that'd accountname Some message here will send a direct message to accountname, even if entered in the public tweet box or via another client. This shows that they have a standard text to action parser that works on tweets as they are submitted.</i><p><i>So, to answer your question: No, it's not down to Jack Dorsey's father. It's purely because Twitter is interpreting it as a command. Sorry!</i>
I find the explanation posted in the question more fascinating than the actual answer:<p><i>while in High School, Dorsey's father used to spur him to work harder with that exact sentence.</i><p>For me, this implies that the creator of Twitter hated his father's trademark phrase, and by extension his father's demands to work harder, so much that Dorsey would explicitly put a ban on the phrase to spite his father.<p>This follows humanity's tradition of creating myths to explain things we don't understand[0], but it's exciting to see the mystery phenomena revealed as something created entirely by man.<p>[0] <a href="https://en.wikipedia.org/wiki/Echo_(mythology)" rel="nofollow">https://en.wikipedia.org/wiki/Echo_(mythology)</a>
Seems likely to be related to the Twitter in-band signalling thing that caused the accept bug back in 2010.<p><a href="http://gizmodo.com/5535536/the-real-story-behind-twitters-ridiculous-follow-bug" rel="nofollow">http://gizmodo.com/5535536/the-real-story-behind-twitters-ri...</a>
It seems odd to me that they would have the same command filter on the web client as the SMS handler. What possible reason would you have for that?<p>Wouldn't it just be smart to have the web client bypass the command handler altogether?
I didn't seem to have any trouble posting "get better":<p><a href="https://twitter.com/jeremysharpe/status/205522693821448193" rel="nofollow">https://twitter.com/jeremysharpe/status/205522693821448193</a><p>;)
Related: you can't create filenames in DOS reserved by devices.<p><a href="http://wiki.answers.com/Q/Why_can%27t_you_create_a_folder_named_CON_in_Windows_or_MS-DOS" rel="nofollow">http://wiki.answers.com/Q/Why_can%27t_you_create_a_folder_na...</a>
Relatedly, there was an in-channel-command bug in Twitter in 2010 that would allow you to force anyone to follow you by tweeting "accept [username]". It was discovered accidentally by a fan of a band named "Accept" tweeting "accept pwnz": <a href="http://mashable.com/2010/05/10/twitocalypse-heavy-metal/" rel="nofollow">http://mashable.com/2010/05/10/twitocalypse-heavy-metal/</a>
I found this to be true with the term 'M$', specifically with the '$'. I didn't think that term was still a thing, and then I came across it in an email. I wanted to note my surprise on twitter, making a ridiculous comparison that I shall not repeat here, but the tweet would NOT go through. Change the '$' to 'S' and everything is cool.
SMS is probably the root of quite a few Twitter restrictions, not just this one.<p>For instance, the length of a tweet. I think it's 140 characters so they can fit it in an SMS message along with the username or command.
<i>"..it's perhaps useful to remember that d accountname Some message here will send a direct message to accountname, even if entered in the public tweet box or via another client"</i><p>d, and and dm as well.