One of the Chaos Run items is the Mohawk. Just equip that one. While you can play online and do you best, there's also an easy way to do this trophy. When you press 'Play Online' you can create your own private match. Do this make it a name/password type. Now change the setting to how you want, which is 4v4 and no bots. Also change the goal limit to 1 so it'll be over quick. Now when you press 'start match' the game will search for a server to host your match, so be patient when this happens.
Now when the match starts, just score into the opponent's goal and pop goes the cheevo!
Additionally, if you use the Scarab or Zippy car, you'll also unlock the Natural Progression
trophy, if you didn't already have it.Edit oct 2020:
Looks like they changed the description of the trophy. It used to be "Equip a Chaos Run item and.." but now it's "Equip the Flamethrower Boost and...". I assume that this was changed because the game went free for everyone. The Flamethrower Boost is obtained through randomly getting it them after playing matches. There are coloured versions of the Flamethrower Boost, however those do not count for this trophy so you need the original Flamethrower Boost.