On one job in 1999, I was asked to convert a Visual Basic / Access application to point to Oracle.
I coded the app, tested and went live.
And the Unix server crashed.
Everyone took notice.
I got called into a meeting.
What did you put in that code to kill the Unix server?
Turns out, the VB app was calling the Access app every 10 seconds, to check for Status messages.
An early form of Instant Messaging.
So 150 users, calling the Unix server every 10 seconds, took it down.
They asked me to disable that feature and they purchased a 3rd party app to replace.
And all was well.