Mobile phones + petrol station = explosion
is a rather random urban myth that, for a truly inexplicable reason, as become part of forecourt law.
Indeed, in my uni years I worked at a petrol station – we had a mobile phone mast built into the price display tower thing (correct terminology escapes me at the moment…)
Generally it's preferable for people to be concentrating on filling up their car. I have fond memories of the chap who insisted that our pumps were faulty, because the fuel had backed up and spilt over his coat, shoes and trousers. He said we'd have to pay for dry cleaning, and that he was outraged, etc, etc. Turned out he was trying to put diesel into his unleaded hire car – the nozzle was physically too big to be inserted properly, hence the fuel going everywhere.
Given the inability of some people to mono-task, multi-tasking is to be discouraged…especially around flammable materials! 😛