Related to previous post is the news that Britain is now requiring would be new citizens to take a citizenship exam.  They have to answer questions requiring them identifying terms like "Boxing day", or what Britons call the Liverpool dialect.

I can think of some others:

Why do Britons have such bad teeth

Why are Britons such horrible hypocrites?

Why do Britons weep and moan over everything when they are supposed to have a "stiff upper lip".

What is a "stiff upper lip" anyway?

How many conquered/subject people did Britain kill from 1600-2000?  Any guess within 3 million will suffice.

Why are British monarchs morons?

Why have almost all great Britons actually been Scotch or Irish?

This is a real quickie list.  There are more and better questions but I am out of time for now.  Any others?