Instructions:

Mankind has spent years trying to contact other space civilizations. There have been multiple expeditions where a golden sheet with an image that represents us is sent to far away galaxies. This time, however, a joker changed the message into something more… insulting.
Aliens deduced from this new message that humans were grotesque and offensive little creatures, and needed to be destroyed.

They’ve come to Earth to destroy humanity! You, and your missile-loaded truck, are humanity’s only hope.