Tea is made of leaves and the juice of leaves has a certain amount of nitrogen and other nutrients. It tends to make leafy gorwth however and it not ideal for geraniums, which do better with high potash feeds.
Banana skins have some potash and boiled-eggs water also has some nitrogen but tiny amoounts. But no ham in recycling the water rather than waste it. All of these ‘feeds’ would have a small beneficial effect, the tea being the most powerful of them.