As creating a drip cake is such a popular topic I wanted to show you this tutorial as well in the basic section. In this way you don't have to sear for a special cake and can just look up how to do it step by step here.
I used in this case white chocolate for the drip but you can also do it with dark or milk chocolate. The white chocolate has the advantage that you can also dye it with food colors. Start the drip with preparing some white chocolate ganache with a ratio of 3:1 chocolate and cream and let it cool down to 50°C if your cake is really chilled (maybe a little colder for a not chilled cake). Fill it into a squeezer bottle and make your trial run on a turned around box. The chocolate should stop running at some point on the vertical surface and please don't make the same mistake like I did myself to not be patient to wait till it has the right consistency. Now you can start to decorate the cake. Squeeze out some ganache right on the edge and let it run half way down the cake. Move the bottle forward half a cm along the edge and do the second squeeze either a little longer or shorter so your drips have different length's. Do this 5-6 times before you go back to the first drip and fill the top surface of the cake about 3-4cm inwards. I always did 5-6 drips, let them solidify slightly till I fill the top area to not have excessive ganache run over the edge but still get a smooth finish on top. This you repeat till you are all around the cake. If you want you can add some food color in the beginning to the cream to dye your drip. If you want to have it more white you can also use white food color.