How to say "unless...?" in the context of "but what if"


In the context of the phrase ["Just kidding...
unless...?"](https://knowyourmeme.com/memes/just-kidding-unless), how would
the word "unless" be translated? Here, "unless" has sort of a connotation of
"what if...?" as well as "unless you want to?"




Or you can just use 冗談でした。。。けど。。。もしか。。。

