Irony and latency
Freud feels that the mature, explicit sexual desires of waking adult consciousness are derived somehow from the earliest memories of sexual longing that one experiences in childhood. These unmet, strange erotic desires lead to the quirks of personality and variety that children demonstrate, and ironically, it is the same intimacy that leads adults to mate intimately through sexuality. Children are an ironic component of sexuality, because it is childhood experience that makes us long for sex, which makes what? Sex makes babies. The cycle is confusing and ironic.
Ironic repression
New sexual feelings are either taken in stride with a blush and a sense of humor, or sometimes, it can happen that someone feels extremely shameful when they discover their sexual intention. For some, that problem can be sorted out by finding an appropriate person to be with who will participate in a loving, intimate way with another person's sexual experience. Then there are the ironic people who repress themselves sexually, or who are given repressive ideas about sexuality from others. For those people, sex isn't about love—it's a cosmic horror fest.
The irony of genital envy
Instead of thinking, "Why should women be treated differently just because they aren't men?" many women experience another kind of emotion during their young lives, if they discover that by having a penis, they would have been automatically more powerful, more serotinurgic, and more preferred by their family, many young girls in this situation feel envy about their genitals. Freud feels many girls are jealous of boys because their bodies are different, which is absurd of course, and therefore ironic, whether it's true or not.
The irony of sexual union
When people come together to provide each other with sexual experience, they are motivated by the longing they felt when they were young, when sexuality was still a latent, darkened part of their psyche. Freud feels that sexuality is about fulfilling one singular sexual aim, which is typically an emotion one was left unable to solve during childhood, and that union is ironic, because the partners co-use each other.
The irony of Oedipus
The Oedipal complex gets a shout out in these essays, Freud's famous opinion that men often suffer from a similar fate as Oedipus who 'loved' his mother and 'hated' his father, by having lots of sex with his mother, and by murdering his father. Frued feels this myth perfectly captures a nightmarish mode of human sexuality where men are enticed by their mothers into a comforting, regressive relationship. The implications of the idea stretch far beyond gender, as a modern reader might notice, but the irony is still as sublime and true as ever. It's ironic that an adult should have to make decisions about their sexual-emotional relationship to their own parents.
