He said the drink tasted of gillyweed. But I think it's actually an Exploding Potion, and would therefore contain a slug besides the key ingredient, erumpent fluid. That stuff is hard to get because erumpents explode a lot. And they tend to blow up each other, too.* We were lucky to find the stuff at CVS; I thought we'd have to hunt for it in Diagon Alley. Considering all the erumpent fluid in there, it was pretty reasonably priced, too.
I didn't actually see a slug bits in the bottle, but they can do amazing things with pulverizing these days.
I hear they'll be giving him Forgetfulness Potion tomorrow. Boy, would I like some of that. I had some once, during a colonoscopy in fact, and I never forgot it. What a lovely experience that turned out to be....
Since I'm going to waiting for him at the hospital for three hours, where I won't have access to any potions, except possibly Starbucks iced mochas in the next building, I think I'll bring along a volume of Harry Potter for some decent company. I'd rather have a butterbeer, but it's a hospital.
* This information comes from Fantastic Beasts and Where to Find Them, by Newt Scamander. I had to look it up; I can't memorize as well as Hermione.