For the non-pilots: if ATC gives you a phone number to call after you land, it means you really screwed up. (It's the number for the supervisor, who is thinking about filing a "pilot deviation report" with the FAA.)

The pilots I know describe these calls informally as,

"Mr. Braithwaite, would you step into my office? Bring your license, and a match."

This thread spurred me to listen to some clips, and I just happened across an 'I'll give you the number when you're ready to copy' example:

https://youtube.com/watch?v=mUSUXnr4dSo

<dj kahlid>Another one</dj kahlid>

https://youtu.be/OrRRMoDC_jA