Not really an appropriate one. The Mask doesn't make everyone silly, how it works is based on deep desires within the wearer. It turned Jim Carry into a cartoon because he has no real talent beyond acting silly he wanted to act silly but was constantly kept in line by his work, and it also turned a mob underboss into the unstoppable badass he wanted to be.



On Pinkie Pie though? It'd probably do nothing. She's dead on the inside and acts silly because she doesn't know how to behave. Since she has no inner desires, it would probably do nothing, or make her like her sister.