heres something ive often wondered,
see guys handing over flasks all the time at various cafes and was wondering, do they just fill it with hot water or coffee tea? can imagine a flask full of coffee would be bloody dear?.. 
i think you will find its just hot water, it saves boiling the kettle.
wirralpete:
do they just fill it with hot water or coffee tea?
Depends what you ask for. 
Most of 'em round here at the tea-coli vans will fill a big flask for about £2 with tea or coffee.