You would either die...............or you wouldn't.
IV caffeine is or has been used in hospitals but only on occasions and only slowly under antiseptic conditions surrounding the IV equipment.
Now i presume that the Ed means using a cup of coffee, that has been allowed to cool, injected into a vein, in which case it would go straight to the heart.......and you would die.
So, dependant upon the degree of sterilisation and the speed of administration, will depend upon the outcome.
Ed.....in future try to place in the correct section.