In Fashionable Nonsense, Sokal and Bricmont draw on quite a few different bits of Irigaray's work, but the one that is most extensively quoted is her This Sex Which Is Not One, specifically chapter 6 on "The Mechanics of Fluids".
Irigaray is writing about the treatment of women and the feminine within the context of western philosophy, and in this chapter she's presenting a case that there is something masculine in the logic of the discrete solid object. Her idea is that the finite logic of syntax in the Frege/Russell tradition functions by first fixing upon a finite and discrete domain, which necessarily involves a process of extension. She thinks this process of extension is specifically psychological, depending upon a cognitive function of judging boundaries and exclusions and treating things as (solid) individuals. Finally, she argues that that function has been specifically coded as masculine, in contrast to how western culture has coded as feminine aspects of fluidity, which has sexualized connotations.
Sokal (standing in for the authors against) is affirming firstly that mathematics takes the continuous very seriously and has proposed very particular theories of fluid mechanics without undermining the classical logic foundation, rather than ignoring it as "other". Secondly, he makes the case that the mathematics involved is used through formulating an idealized model rather than imposing that structure upon the world as a matter of "the Real"; that mathematics creates models and structures, rather than imposing itself upon the world as such. Finally, he criticises Irigaray on what he sees as an idea that mathematical reasoning might be somehow beyond the dispositions of women, who are perfectly adept themselves at understanding the tools of sets, probabilities and geometries that Maths has proposed.
I think there is a lot to be said in defense of both parties here, but I think Irigaray's position is much less threatened by Sokal's response than might be concluded given the Wikipedia article.