Batman and Two-Face get hit with a de-ageing gun and become teenagers again. Chaos ensues. (Could be a great idea for a Bruce/Harvey fanfic.)
How does Gotham deal with temporarily losing its main superhero and a supervillain? How does the Batfamily and Justice League deal with this?
You can obviously choose what you want to happen but it would be funny for the Batkids to expect their dad to be sad and angry but he's the opposite, dancing on tables, drinking, partying, flirting, singing loudly (like belting 80s pop songs).