I mean agitating the carbonated fluid makes the gasses dissolved in it escape, in this the reason? (I think it should have been, obviously this is the reason)
Carbon dioxide is dissolved at high pressure in the can and when the can is opened the reduction of pressure results in the gas coming out of solution.If the can is shaken beforehand the pressure is increased further due to the reason given by dE logics but with time the gas dissolves again.Tapping the can may reduce the time needed.
humm...trapping the gas will increase the pressure which will aid solubility with of the gas, as a result when compared to a case when the bottle was not blocked, the amount of gas that vaporizes should be more.