For this trophy load up Goatville and if you head north east of the spawn area you should find a rocky kind of hill and then a fire lit path to the devil goat symbol on the ground of the Baphomet pentagram as shown in the video at the bottom of this solution.
All you need to do is use your tongue next to a human NPC by pressing
and this is your way of grabbing things by using your goats tongue and being able to drag them around with you. So follow the video, i grabbed the first NPC you see just outside the fence where you spawn and then just down from the ritual pentagram there is a BBQ party going on with 4 people there, they may run away but they don't get far, the AI is pretty stupid making them easy to catch if they somehow become unstuck from your goat tongue.
Once you have all 5 humans placed on the Baphomet pentagram the ritual will start and you will unlock the Devil Goat and with it your trophy.
So if you feel comfortable performing a devil worship ritual with a goat and 5 humans it will gain you a silver trophy
Do not worry, you can redeem your self with the Angel Goat trophy afterwards if you have not already done so which i have a solution for here.
(The solution may not be showing just now because of a site issue but it will be up as soon as it's resolved)