Someone who has been 'holding in' a shit for a period of time, thus allowing the faeces to 'cook' or 'bake' inside their anus.
Usually occurring through lack of toilet facilities although some bakers have been known to bake for pleasure,fame or purely just the for the craic.

a shit so thick and creamy that if squeezed through a pastry bag it could decorate a cake.

When there is way more than a Baker's dozen, a shit ton, "A Baker's Shit Ton".

not too solid and not too loose...if you could shit into a pastry bag and decorate a cake with it.

a shit so thick and creamy it could fill a pastry bag and decorate a cake.

a shit so creamy and thick, if placed in a pastry bag it could be used to decorate a cake