Our party(lvl3 babies) found a sending stone and we are pretty sure it's linked to our bbeg/at least this arc's villain and i was wondering what are fun things to do with this.

Some potentially relevant context : We don't think the bbeg is actually familiar with us, so they may not even know who is sending, they just know it's not the original owner of the stone(from what I understand of the sending spell rules). This villain is the head(or a higher up) of a secret organisation that borders into terrorism. We took the stone from an informant of the bbeg after he gave them info on the location of an important artifact they're after.

There's always the common trolling, sending bullshit just to be annoying but I think it's been done a lot. We could also be upfront about who we are and entertain a rivalry at a distance, allowing for fun interactions before actually confronting them. But what are your fun ideas, O great hivemind of the internet?