These spiritual crocodiles can kill or mutilate your souls. They can destroy your peace of mind and the peace of mind of those who love you. Those are the ones to be warned against, and there is hardly a watering place in all of mortality now that is not infested with them.
Elder Boyd K. Packer, "Spiritual Crocodiles", General Conference, April 1976
This is, and has been, one of my favorite talks. When Elder Packer was in Africa, he noticed that crocodiles could hide themselves in the tracks left behind by elephants. These tracks would fill up with mere inches of water so one wouldn't expect a crocodile there. The crocodiles could remain unseen, waiting patiently for unsuspecting animals who become thirsty. When those animals approached, the crocodile would lunge forward and grab that animal, dragging it to its utter destruction.
The lesson, of course, is that there are spiritual crocodiles everywhere, hiding in mere inches of water, so thereby we assume that there couldn't possibly be danger there. Or, we just don't pay attention at all and act nonchalant when we go "get a drink of water". But, that's when these spiritual crocodiles attack, or when the adversary attacks....when we aren't expecting any harm.
His point of the talk is to listen to our "safari guides" to avoid those watering holes that are hiding danger. And those guides are, of course, parents, bishops, leaders, Prophets and Apostles, and other servants of the Lord....and, especially, the Spirit prompting us through revelation. These guides are warning and will continue to wrn which watering holes to avoid and which are safe so that we can drink the lifesaving water that we need.