The one and only call on January 1st
Working for support services of a , at that time, famous Unix systems company. Although we warned customer not to shutdown server and disk systems , there was one customer who exactly did that. And guess once, when the Sun set that day, the system didn't want to boot anymore and customer didn't had a 24/7 support contract. So he called the local support center ( staffed with engineers around the clock, all night no work, backup mobile phones of all local phone companies, nice food, playing Quake over the company network , extra bonus paid ...). Yes , sure he would pay the premium price for an intervention on January 1st. Support Engineer came on site, gave the disk a slight slap and the system started booting without any problems. Guess that must have been the best paid slap in IT history.