Ok so a water sommelier is pretty ridiculous but there is definitely a difference between different waters, particularly tap water in different places. Tap water in London for example is almost undrinkable (to me) but Scottish water is really good.

Those are actually 2 different Gregorys (Gregories?) with almost a 1000 years between them. This may be pedantic I feel like that's in the spirit of the original joke

Charade 1963