Re: PRASAD
PCG good humor..
If you have eaten it by mistake ask for forgiveness and pray that it never happesn again. Shaytan can play 24x7 with you if you let him.
In the case of receiving prasad and it is some friend giving it to you, take it and give it to some poor Hindu or kindly explain to him/her about your belief.
It is obviously not permissible eating anything that has been offered as ‘Prasad’… check this fatwa http://www.shariahboard.org/viewfatwa.aspx?Question_ID=7237