Boisterous; moisturize. Someone I know pronounces boisterous as bois-cher-us, which drives me crazy. Today I realized that I say mois-cher-ize.
Why the difference? Or is it just me? (You all may take that any way you like!)

I say them both the same as you Jackie or so it sounds to me!

/ˈmɔɪstʃəˌraɪz/ is the usual NA way to pronounce moisturize. Presumably it used to be /ˈmɔɪstjuˌraɪz/ and the /tju/ was palatalized to /tʃə/ - as it was in future, nature, culture.

But boisterous never had /tju/ so the pronunciation /ˈbɔɪstʃərəs/ maybe came about by analogy with words like moisturize, nature, etc.

well, one is TER and the other is TUR so one might expect a difference in pronunciation, no?

I don't think most dialects pronounce the ur in moisturize and the er in boisterous differently.

I thought about that, Buffle. If I'm being careful I say mois-cheeyour-ize (or something like that!); but most of the time, I'm not that careful.
There was a yew sound in there, I swear there was...