English is spoken on both sides of the pond, so you may think you’ll have no language issues when traveling between North America and the UK. Think again. There are actually quite a few vocabulary differences between the two, some of which may cause confusion or miscommunication. More often than not, it will just cause amusement. This is not a list of slang or idioms, but basic words you might encounter on a trip across the Atlantic. One is not necessarily more “proper” than the other, just different. Here’s an American’s guide on how to speak British English, or visa versa.

1. Knock Up

If a London lass asks you to knock them up at 8am, they are not suggesting a morning booty call. “Knock up” is Brit-speak for “wake me up”, whereas in America it means “impregnate”. See how this could lead to some awkward misunderstandings?