Is it pineapple or grapefruit juice that supposedly improves the taste of cum ?

I have a special lady I want to give a treat to next weekend. How many days before the encounter should I be drinking it ?

Probably just put up with it just for the $$$.

But does it actually work?

pineapple juice or whole pineapple / canned chunks also will do.

You can also take pineapple/papaya enzyme tablets (chewable, not unpleasant tasting) from Trader Joes. It probably won't improve it to where she's wanting it for a dessert topping, but it will make it noticeably sweeter, less bitter.