steph and cass have developed a code (a lot of it is gestural, but some of it isn't) that only they know, and they use it to talk to just each other in all sorts of situations (esp when they really shouldn't). the rest of the family knows about its existence, but none of them can crack it bc steph and cass are always changing things and adding weird inside jokes to it. steph very intentionally will obviously say something to cass in code in front of the other family members just to make them question if she's talking about them (sometimes she is, but sometimes she's just saying random shit bc it's funny, or even nonsensical things). cass thinks this is very funny, so she always goes along with it. they also use it while doing vigilantism, and if questioned about its existence, they're always like well it's very good for bat stuff.
