As the world prepares for the wedding of Prince Harry and Meghan Markle on May 19, all eyes are on the UK. But even though we share a common language, there are still a few cultural matters that prove difficult for Americans to understand.

In order to ease culture shock, British Airways asked its flight attendant ambassadors to answer pressing questions from American tourists.

From the ingredients in a “Scottish egg” to the pronunciation of “aluminum,” the cultural emissaries unpack an American beginner’s guide to London.

Cultural differences tend to come out over the dinner table. It turns out that most Brits don’t understand why mushy peas are ubiquitous, either. But, rest assured, no matter the size of the filet on your plate of fish and chips, it’s probably just cod or haddock.

There’s also the question of tipping. Much like portion control for meals, tipping is smaller on the opposite side of the pond. The Brits generally leave a 12.5 percent tip at a restaurant or pub. However, the British Airways ambassador assures viewers that nobody will be offended by “American-sized tips.”

The British Airways video tells American tourists that the U.K. is “a polite nation,” although citizens do have a tendency to joke. “If we are pulling your leg, there’s always a sparkle in our eye,” an airline ambassador explains.

So, be warned: If you’re heading to the U.K. to celebrate the royal wedding, you don’t have to order the mushy peas, tip less, and be prepared for a jolly minded prank.