"That's a good idea, actually," Karla assured him. "You could also float oleander blossoms in the lemonade until right before serving, then strain them out and replace them with other, non-lethal blossoms, like hibiscus. That will add both to the toxicity, if that's something you're worried about, and also provide a reason if the lemonade still tastes a little funny. Rosemary or thyme also works in this situation."