It's the Powerup Cancellificatinizer. I don't know an exact spot for one but it is definitely a rare find so all I can recommend is just looking for barrels in out-of-the-way/hard-to-reach areas
Thanks! Strange that this rather useless PUp is so hard to find. I mean, debuffs generally don't last that long.
Do you happen to know what kind of barrel it's in? Red/black/blue etc. I googled it, but not much information seems to exist for C:MD and C:R.
Edit: Got it! Black question-marked 'barrel'/tires.
Only thing that's left now is the multiplayer-related unlocks and achievements. *sigh* Never mind that, I guess.
Reading around (and seeing this site constantly be unreachable) I see the developers have pretty much abandoned this game. I wish one of them would at least write a little tool or something, so people could unlock everything multiplayer-related. I asked them this through their support website a while ago: No answer.