Confession : I was made to do this on my very first A380 flight (although, mercifully, was in normal clothes rather than PJ's).

One of those oddball scenarios where you initially think "oh that's so warm & friendly of the crew, what a nice gesture ....." And then - around 30 seconds later - you realise they just want a good laugh for themselves, and have identified you as the candidate likely to look the most ridiculous