pray to the porcelain god

To pray to the porcelain god means to be throwing up or vomiting into a toilet. The toilet is often known as the porcelain throne as many toilets are made of porcelain or at least have the same look and appearance of being porcelain. Therefore, this idiom is often used to describe someone who is vomiting into the toilet because they are on their knees, with both hands around the toilet bowl as if they are praying to it.