Here is the full list of all 20 Boo! Greedy Kid achievements.
Shout on your first victim
Shout on 200 persons
Finish your first level
Finish one third of the main campaign
Finish two third of the main campaign
Finish all levels
Get one third of all the stars
Get two third of all the stars
Get all stars
Hide behind a furtinure 100 times
Dodge roll 100 times
KO a nurse
Taunt someone with your butt
Get tased
Get caught by a robot-cop
Slam a door in the face of someone
Slam a door by rolling through it
Earn $5000
Finish a level with just one hearth remaining
Shout on a SWAT