I was leaning towards fuckletoes also, never heard dicksplash although it wouldn’t be a surprise, but really any of them would generally be appropriate. You’re supposed to get a little creative from time to time.
My favourite one that not so many people have heard is “that’s rare as rocking horse shit”.
Ejaculation is supposed to refer to written statements, though. As in, Watson ejaculated over Sherlock Holmes. (He literally did, the word is used all over the books).