Where's the Beef? Achievement Guide
For this trophy you have to "Tenderise a Bull with your bare hands. To death". You can find bulls at the Sunset Threshing farm in Holland Valley.
Note: To make this trophy very easy, simply craft a "The Furious" homeopathic (2x Bliss Oil and 2x Paririe Fire). With this active you will kill the bull in once punch.
Ignoble Beasts Achievement Guide
A similar achievement...