Then we saw another old man, called Abba Bes, who surpassed everyone in meekness. The brothers who lived round about him assured us that he had never sworn an oath, had never told a lie, had never been angry at anyone, and had never scolded anyone. For he lived a life of the utmost stillness, and his manner was serene, since he had attained the angelic state. He was extremely humble and held himself of no account. We pressed him strongly to speak a word of encouragement to us, but he only consented to say a little about meekness, and was reluctant to do even that.
Once when a hippopotamus was ravaging the neighboring countryside the farmers called on this father to help them. He stood at the place and waited, and when he saw the beast, which was of enormous size, he commanded it in a gentle voice, saying, “In the name of Jesus Christ, I order you not to ravage the countryside anymore.” The hippopotamus, as if driven away by an angel, vanished completely from that district. On another occasion he got rid of a crocodile in the same way.
Historia Monachorum in Aegypto 4
The takeaway: if you have a hippopotamus or a crocodile problem, find a local monk. This directory should help.