Absurdist drama is about the illogical nature of the world and its lack of meaning. The main character in The Birthday Party, Stanley Webber, is an unemployed pianist, but he asks Meg, who runs the boarding house where he lives, "I haven't got a piano, have I?" Stanley is unaware of even the basic nature of his existence. Later, Stanley tells Meg, who is celebrating Stanley's birthday, "This isn't my birthday, Meg," even though she reassures him it is. Stanley is unsure even of when he was born, showing his alienation and uncertainty about the world.
When two agents named Goldberg and McCann arrive to question Stanley, their questions veer into the absurd. Goldberg asks Stanley, "Who watered the wicket in Melbourne?" and McCann adds, "What about the blessed Oliver Plunkett?" Goldberg and McCann continue to ask questions that have no answers as they grill Stanley. They use this absurdism to torture Stanley. However, conversation in this play has no meaning, and words are only used to confuse people. The confusing nature of words supports the idea that the world is absurd and that the search for meaning is pointless.
Absurdist theatre examines ideas of existentialism and the meaninglessness of human existence. In The Birthday Party, the protagonist, Stanley Webber, has committed "existential transgressions" which are brought to light by the arrival of two men, McCann and Goldberg, at the English boardinghouse where Stanley is hiding out. Stanley's ultimate crime is a crime against the self; he withdraws from the world and is stunningly apathetic.
The absurd psychological interrogation that McCann and Goldberg submit Stanley to causes him to lose his senses and have a breakdown. He becomes complicit in his own role as a victim who cannot control, change, or ignore his fate. His crumbling identity and eventual loss of speech capabilities make a very absurdist statement: life is without purpose and communication is futile.
The play The Birthday Party is considered a part of The Theatre of the Absurd because the main character, Stanley Webber, finds himself lost in a nonsensical world that he can't make heads or tails of. This is the defining feature of absurdist fiction; one or some of the characters are unable to make sense of the nonsensical. Two people show up claiming its Stanley's birthday, despite his protest and insistence otherwise, and refuse to let him leave his home. A birthday party begins to unfold as a total nightmare for Stanley eventually rendering him a broken mess.