Does anyone know how the magicians perform the glass in the coin trick?

Question:

Does anyone know how the magicians perform the glass in the coin trick?

I know about coin in soda can and it is not transparent, so there is no chance that they put the coin after opening the can, but glass is clear transparent and I was amazed to see that they just smack the coin and inside is your coin. ANY LINKS.

Best Answer - Chosen by Asker: Yes, I know how we do it.