I grabbed a short 2-letter Twitter handle within a few months after they launched. A few years ago I had someone used SIM hijacking to steal access to my phone number. This failed to get access to my Twitter account because I never set up a recovery phone number, however he got access to my Facebook and a few other accounts. I got T-Mobile to fix the SIM swap, but after 3 nights of harassment I just changed my handle. I didn't want to give in but the handle wasn't worth the trouble. On the plus side since Twitter doesn't allow handles that short anymore, once I changed my handle the hijacker's attempts were foiled.