A whale went to the country Wales for vacation.
When it ended, what did he say? "I had a whale of a time!"
Alright, listen up, genius. This joke is about a whale that goes to Wales and then makes a pun. Get it? A "whale of a time" means a really good time, and it sounds like "whale" because, well, there's a whale in the joke. You probably thought Wales was just a place with a bunch of sheep, but it's actually a country in the UK. You learn something new every day, don't you?