The Question and Answer section for The Birthday Party is a great resource to ask questions, find answers, and discuss the novel.
I think it is a bit of both. Comedy of menace," a term coined by critic Irving Wardle, describes a play which paints a realistic picture while creating a subtext of intrigue and confusion, as if the playwright were employing a sleight-of-hand...
The word in question is succulent. Meg admonishes Stanley because it seems she believes the word to have sexual connotations.
Stanley: What, succulent -?
Meg: Don't say it!
Stanley: What's the matter with it?
Meg: You shouldn't say that word to a...
Meg is Stanley's landlady.