Bizarro is brought to you today by Invaders.
If there is one thing I've learned in my bazillion years as a syndicated cartoonist it is that there are lots of people who don't get any given cartoon. Especially if it has a history reference in it.
For those folks, the British Invasion is the name given to the many British rock bands in the late sixties that were so very popular in the United States. The term was a play on words in reference to the British invasion of the colonies during the American Revolutionary War. The War of 1812 would be another famous example of the British invading something.
Today's cartoon formula: Old guy still dressing like a mod from the sixties attempts to hit on young woman by making an outdated reference and she shoots him down with history. Who said that stuff we learned in school wouldn't come in handy some day?