I must say that in the partially joking vein of my question I was quite curious to know what a "module that contributes to one's hubris" could be, even before knowing which actual modules people would suggest.

Indeed boasting with friends contributes to one's hubris, so any module that helps us writing software that we'll proudly show to friends is a good candidate. Unfortunately I can't think of very good example myself. Probably

• File::Find
• Proc::ProcessTable
• Digest::MD5

since afaict they're the ones I used most in small utilities I felt comfortable enough with to distribute to firends. (Well, if we exclude strict and warnings that indeed help me to write code I can feel proud to show off...)