Characters
Monastic humor. I miss out on all the fun.
— Wash ‧ Firefly

Behind the line May contain spoilers.
Our reading
An editorial interpretation.
The speaker wryly labels a joke as 'monastic humor' and then laments missing out on all the fun. The mock complaint suggests a life of restraint where amusement is scarce, with the comedy coming from treating self-denial as a punchline at the speaker's own expense.
Context reviewed