I have found that when I ponder random questions like this...that google is my friend (and Wikipedia is a close friend too!)

Of course, now my brain is full of thousands of useless facts....unless I'm playing trivia at a bar.....

Spermaceti Whales...highly prized oil!

Because Ejaculation Whales sounds silly.

Its because during whaling when they were regularly butchering whales, they discovered a liquid inside the head that looked like sperm so that's what they called the whales. I used to work at an aquarium and a kid asked me that once, I quickly thought uh, ok, let's go with the truth and told her that and then internally pleaded, "don't ask me what sperm is, don't ask me what sperm is..." and she just said "ok!" And went on her way ?

Because the oil harvested from these animals (the oily fat in the article) was originally thought to be the whale's semen (and hence called spermaceti literally whale sperm). Spermaceti whale was shortened to sperm whale.

Just don't get in the pool with them to find out!!!