The Goo-Jar is found in the Caduceus level, so your best bet is to pick up the jar next to your trunk on the observation deck that's overlooking the main... vivisection area? I don't know what to call it lol.
Once you clock out with satisfactory performance, take it with you to the next job by keeping it in your trunk and chuck it at a corpse. I don't know if this specifically needs to happen but it did break when removing it from the chest and I didn't get the achievement, so I reloaded and tried it again by throwing the vial at a corpse and that made the achievement pop.
There is also a Bob note on the level, so be sure to have both of those things.