http://dictionary.reference.com/browse/caulk
this link seems to agree, with the word represented in IPA as [kɔːk]
Being a french speaker, I would say pronunciation is closer to "puck" with a k, so go with "Kuck".
It's the cot-caught merger.
Using the name of this language in a workplace creates a hostile working environment[1]. That guarantees that no sensible person in the English speaking world will ever use the language at work.
[1] https://en.wikipedia.org/wiki/Hostile_work_environment
Oh my, thanks for the laugh. I half imagined a Dilbert scenario when reading that.
It's weird to think of the simultaneous uptightness and childishness which would make it impossible to use this homonym in the proper context.