
Fatuous
Negative Connotation
The word 'fatuous' often implies a critical or disapproving tone when describing someone's actions or remarks. 
Not Always Humorous
'Fatuous' may sound like 'funny', but it actually criticizes a lack of seriousness or thought when it's needed. 
Informal Context
Use 'fatuous' in informal discussions and writings where a more conversational tone is appropriate. 