Twitter question

[Blame]

I'm pretty sure you can't but just making sure. Can you swap Twitters under 5 characters. ie. 3 characters or 4 characters. ​

 

[Homie]

You can swap 5 letters. but not 4 and under.

 

[Blame]

So how easily can 4 letters be pulled back? Is there a way to fully secure them? @Homie