Yorgos Lanthimos refuses to explain his films, and although the influence of Buñuel seems apparent, there are obviously more influences at work here. Some kind of satire is going on here, but of what nature is open to question. This is another huis clos, and if humorous it is also highly sinister as this horror-tinged film takes its course.
The parents here are crazy, and have shielded their children (now adolescents) from reality so much that they only live in the family home, surrounded by a large fence, and know nothing of the outside world which their parents tell them is full of horrors. The parents have even invented a new vocabulary in which a sofa is the sea, a plane is a toy, and a zombie is a yellow flower. Cats are very dangerous creatures which eat people.
The son's sexual needs are supplied by a security employee from the husband's place of work, who is driven to their home blindfolded. But it is this woman's need for oral sex, which the son won't supply, that leads to the woman seeking it from the elder daughter, and this relationship will eventually lead to a breach in the closed world. Stranger than Buñuel.