What does this question is really asking about: " What do you sleep in at night?"

Question

This is from a native speaker's show ellen and victoria (see:1:10-1:15)

Ellen: What do you sleep in at night?

Victoria: Heels.

I could not quite understand what she meant by her question. It just did not make sense. I looked up "sleep in" and verified that it means "getting up later than usual time in the morning". But then why does Ellen say "...at night?", because a "sleep in" is something that can only happen in the morning.

Another meaning is "to sleep in the workplace.", which again does not seem to make sense.

Finally, what is she really asking about by using the question word "What"? "What" does not make sense in terms of "getting up late". We don't ask anyone "what do you get up late?", do we?

So, is she asking about "What TV program" does she watch at her workplace that causes her to wake up later than usual the next morning?

Answer 1

The questioner is asking 'What do you wear when you sleep at night?' and an appropriate answer might be 'pyjamas', 'a nightdress', 'nothing', etc. The answer 'heels' (high-heeled shoes) is a joke.

If we talk about what someone does something in, we are generally talking about what relevant item of clothing that person wears when doing that thing.

What do you go running in? Trainers.

What do you sunbathe in? A bikini.

What will you get married in? A white dress.

Answer 2

This is an interesting question because it brings up a curious fact of English.

If you say, "I slept in", that means, "I slept later than I usually do", or perhaps, "Later than most people do". Like if you normally get out of bed at 7:00 am but today you didn't get out of bed until 10:00 am, you might say, "I slept in."

But if you say, "I slept in my work clothes", you mean that you were wearing your work clothes when you went to sleep. (Like you were too tired to change into pajamas, perhaps.)

And in a third sense, if you say, "I slept in my car", you mean that you went to sleep in your car. As opposed to at home in bed where most people normally sleep.

In this case, the person asking the question is almost certainly think of sense number two: What do you wear when you sleep. Most people would say "pajamas" or "underwear" or "I sleep naked" or some such. The answer "heels" is a joke. It's an unexpected answer. To ruin the joke by explaining it further, most people don't wear shoes of any kind to bed, so saying what kind of shoes you wear is unexpected. Maybe I just have a dirty mind, but I take it to mean "high heels and nothing else".