Have you ever worn your pajamas outside of the house? Likely you have done so, at least once, for some reason. On 1000 Awesome things wearing pajamas outside the house has become #306 on the list of awesome things. On that post they give situations where you might wear pajamas outside: picking someone up at the airport, college dining hall, walking the dog, picking up milk at the corner store.
I’ve never worn pajamas for any of those things. I have worn pajamas when I went out to the drive-in movies, when I went out to pick up the mail/ newspaper or to take out the garbage. Probably some other things I’m just not thinking of right now.
Make your own list for wearing pajamas out of the house.
Then come up with a situation, unusual and creative, where someone would end up being in pajamas (or a nightgown depending on what you usually wear to bed) and get caught outside.