Our HQ was in Germany, so were usually an hour ahead of us in the UK.
Once we had a network problem, so I rang them up at about 4.25pm (UK time) to let them know. The phone rang, and then silence.
So I rang again, same thing. I thought they'd all disappeared off home early, and muttered "Bastards!" as I hung up.....
A few minutes later, someone rang my number and said "er... hello.... you called us bastards?"..... It turned out they were still in the office, it was just they could hear me, and I couldn't hear them... oops!
I apologised profusely, and they were surprisingly OK about it.
For several weeks afterwards they signed off their emails to me with "from the German Bastards" :)