I recall a tale from the first place I worked back in the 90s. Engineers would from time to time phone the local sports club to book squash courts. The beancounters got wind of this and had a call block put on the number.
However the company was one with a myriad of offices and partners all round the world with a tightly integrated phone system, and the beancounters were obviously not used to dealing with a lab full of very tech savy engineers, who soon worked out that even on the most restricted extension you could dial another office switchboard, and from there hop to another and another. So it did not take long for them to come up with a route that would get them back to the sports club. The only downside was the 26 digit number they had to dial.
Needless to say the long number stood out on call reports like a sore thumb! The beancounter went on the warpath to complain to the teams engineering manager, demanding that he tell them off and stop them doing it again. To his credit, the manager told the beancounter that he thought their solution was brilliant, and he would do no such thing! He said in fact he would go and congratulate them, since it displayed exactly the right kind of inventive problem solving skills that the company needed.