1986: Poetica Vaginal
Joe Davis is an artist and a research affiliate at Massachusetts Institute of Technology. In the mid-1980s, he became concerned that no image of humans had been sent into space representing the details of human genitals or reproduction.
So he led a project to transmit the sounds of vaginal contractions towards neighbouring star systems. To do so, he recorded the vaginal contractions of ballet dancers.
The messages were to be sent from MIT’s Millstone Hill Radar to Epsilon Eridani, Tau Ceti and two other stars. However, only a few minutes of footage was transmitted before the US air force, which had jurisdiction over the facility, shut the project down.
Nevertheless, the vaginal sounds that were sent will have reached Epsilon Eridani in 1996 and Tau Ceti in 1998. It is unclear what sort of reply we should expect.

I can imagine superintelligent alien race with mad skills in solving inverse problems spending centuries solving the signal. When they eventually have working models of vaginas and ballerinas, they can listen The Nutcracker. Probably they send us message back saying something like: "OK. that was weird!"