Nice one
Well vanishing a coin is not original. Coughing up the coin was good (very well acted

) but you don't need to use the french drop in that case. AS you acted as if you had put it in your mouth, wouldn't you have just been better to
actually put it in your mouth?
An alternative presentation you may like to try is to do the french drop, and direct attention to the hand 'with the coin in' as you 'vanish' it, (you can then pop the coin in your mouth while they aren't looking), then it will seem that the coin vanished from your hand and
reapeared in your mouth!
...oh and don't worry if it's original or not. What does it matter?