There is little that can compare to the pleasure of drinking from a
large pack of takeaway ABC Special in front of the office workstation.
Even on a cold day. ;)
Anyway, the trick to drinkable (through a straw) ABC Special is to
get the proprietor to agitate the concoction (or in less pretentious
terms, shake the damn thing) beforehand. It may be necessary to leave
the bag standing beside your monitor to thaw out at some point. This is
perfectly normal and you’ll know when to start drinking again when the
bag starts to tip over, indicating a state change into liquid.