I once had a business meeting close to the US headquarters of Hewlett-Packard and with me in my group was this very sweet lady from the UK. And because we wanted to avoid traffic and get to the meeting location in San Francisco in time we had to get up early. And so she said to the (male) hotel receptionist: ".... and please make sure I get knocked up early in the morning ... "
You should have seen the guy's face.
"Ahem ... say what again? No ma'aam, I think I can't do that!" to which she responded "WHAT? What's wrong? Knock me up. What's the problem .... ?!"
The rest of us European guys who were aware of the misunderstanding had to clear this mess up before the situation escalates.
Unnecessary to say that once we informed the lady of what she had asked from the receptionist it was quite embarassing. I guess she will never use that verb again, at least not in the US.
In case anyone (e.g. the non-native English speakers here) did not understand what the problem is:
"to knock someone up" means to "make someone pregnant" in US English. But in UK English it means "knock me out of my bed so I wake up". That's what this English lady wanted: She wanted to be woken up early in the morning. She wasn't aware of the other meaning in US English ....