Ezekiel 23 begins with Ezekiel telling us that he is speaking the words of God, and then he tells us the story of a man who wedded two sisters who were once prostitutes in Egypt, but then married him, and changed their names to Samaria and Jerusalem. Any person with a minimal knowledge in the history of the Jewish people realizes right away that the man symbolizes God, and the two sisters are the kingdoms of Israel and Judea. Then, continues the parable, the eldest sister prostituted herself to Assyrian lovers, and ended up being killed by them (in other words, Israel started to worship Assyrian gods, and ended up being destroyed by Assyria), while the young one survived, but became an even bigger whore than her sister. He blames her that she did not free herself from the corruption that was instilled in her back in Egypt, and now sleeps with everyone: Assyrians, Babylonians and whoever comes. In verse 20, he describes how the Egyptians corrupted her, and said that she lusted after Egyptian lovers, whose flesh is like the flesh of donkeys, and whose sperm is like the sperm of horses. Ezekiel is basically equating worshiping other gods with bestiality, and tells us that to worship any other god than the God of Israel is akin to sleeping with horses and donkeys.
The traditional English translation, known as King James' Bible, is quite faithful to the Hebrew original:
"For she doted upon their paramours, whose flesh is as the flesh of asses, and whose issue is like the issue of horses."
But apparently Americans today are unable to read English, and need translation to Americanese. There are many new translations of the Bible, and with every new one, the verse went slightly further away from the source...
Ooh! Kinky! Now we are talking about giant donkey dicks and massive ejaculations. Ezekiel wanted to disgust us, to make us feel like we are sleeping with a donkey, but in the new translations, it became a man with a penis as big as a donkey's, and the verse becomes alluring.
How did this subversion happen? I suppose it is because these translators grew into the modern world, and knew the expression "hung like a donkey". So when they saw the end of the sentence mentioning horse sperm, they translated "donkey flesh" into "donkey genitals" (there is no basis for that in Hebrew). And generations of Evangelists are now reared on this verse, and don't know how to explain it to their children...
Many of them, of course, also miss the symbolism of the chapter, fail to understand that it is a parable, and just read it straight. A Google search shows confused Christians asking why God uses such a language (since it is, remember, the word of God...), why he is so impressed by how Egyptian men are hung, and why he sees fit to bother us with a story about hookers. And nobody knows what to answer.
Worse, today there are Muslim clerics who use this verse to show Christians that their Bible isn't holy, and again, the Christians don't know what to answer them.
I'm telling you: by the time the Americans are done with it, they will turn the Bible into a great porn mag.