A mating ritual involving an intricate non-melodic vocal performance. The similarity between this mating ritual and language used to communicate information is purely coincidental and has lead to much confusion.
Alan Sokal's recent attempt to communicate with post modernists had mixed results; the post modernists attempted to mate with Alan, but no offspring have yet been reported. Exactly how post modernists reproduce, and if they can breed with humans is still being researched.
"'Insert random noun' is a socialist construct" translates to "ooh baby, don't you look sexy. Do you like it post modernism style?"