Bully
50 Achievements
Smell Ya Later
Hit people with stink bombs 50 times.
How to unlock the Smell Ya Later achievement in Bully - Definitive Guide
Personally, I stayed in the boy's dorm room and lobbed as many as I could, that way I could restock quickly and rest or pass out and still be in the same area. Complete Chemistry Class to make stink bombs in your room.
Stink bombs are a throwable weapon that can used to temporarily slow enemies down by creating a cloud of green gas around them. They can be found in random locations throughout the game, and can be purchased from the Comic Book store or created in your room once you have completed class Chemistry 2. In order to equip stink bombs press to scroll through your weapons and then hold to aim at someone and then press to throw them.
In order to unlock this trophy you must successfully hit 50 people with stink bombs. This means that 50 people need to be affected by stink bombs in which you through. As such, you can throw one stink bomb and it may hit more than one person. Depending on how often you use stink bombs this trophy will likely unlock through natural progression of the game. However, the easiest and quickest way to get this trophy is to wait until you have finished class Chemistry 5 so you can make an unlimited amount of stink bombs each day in your room. The boys dormitory is usually packed with people, so just keep spamming stink bombs at people walking around and the trophy will eventually unlock.
You can track your progress for this trophy in the Stats menu by pressing and then navigating to Stats > General> Pranks > Stink Bomb Hits. The below video shows how to unlock this trophy using the above mentioned method.