It is raining cats and dogs
Origin: nobody really knows the exact origin of this phrase. Some people think it came from the old English word catadupe, now obsolete, that used to mean waterfall. Another theory is that it is from Odin one of the Norse Gods, theory has it that cats brought rain and dogs were involved with high winds.
Yesterday America was playing football against Medellin and second half of the match was cancelled because it was raining cats and dogs.
A skeleton in the closet
The exact origins of this saying is unknown. I have heard that it could be related to medical research in the eighteenth century when it was illegal to use bodies for experiments. So doctors would buy the corpses from grave robbers and hide them in the closet. If you have a skeleton in the closet it means that you have a dark secret hidden away that no one must know. If it is found out it could lead to your downfall. Several high ranking police officials have been arrested recently because of skeletons in the closet.