This was from a conversation between Senator Finch, and Pikachu getting drunk please wait shirt Luthor earlier in the film. Just before the explosion, Finch could smell something on her desk. If you didn’t know, urine, when you aren’t drinking all water, does have a very potent smell, so it’d definitely get your attention. She turns the bottle clockwise and notices the label. She looks to where Luthor was supposed to be sitting, and he isn’t there. She then realizes something is about to happen. She doesn’t know what exactly, but she can feel it. The bottle of piss was a last jab at Finch, just before killing her.