What would it be? I don't know, maybe "bourbon"? Or maybe something like "wussy," always directed at an increasingly frustrated and annoyed Archer? Or maybe they make him a toddler-genius, able to pick up every word spoken to him, every word, that is, except "Archer" (with the same result: an increasingly annoyed Archer).
In the course of the episode we might also find out what the Wee Baby Seamus's mom (Trina?) has gone on to do after retiring as a call girl (or is her SEP doing so well that she doesn't have to work at all?). Could be fun; just a thought.