[koz1000]

My last name contains the character sequence "rz".

Back in the BBS days this would trigger a Zmodem transfer on certain clients. It made a lot of people upset.

[dsr_]

If you were using a dial-up modem and sending raw data -- extremely common -- then sending +++ATH0 would cause most modems to hang up.

If you could get that sent over to someone else, their session would be abruptly terminated.

(Hayes patented requiring a no-data-sent time between the +++ and the ATH0. Avoiding the patent but being otherwise compatible introduced the vulnerability. In-band signalling is usually bad.)