There is a similar discussion in the swiss sub forum.
I last experienced it from DXB to ZRH on LX were the guy changed into his PJs for everybody to see things I would have rather not seen. (Hint: No Underwear). We came to the conclusion that we are quite a few people who have experienced it at least once.
(A support group is in the process of being set up)

I‘m not sure why this happens so „frequently“ on LH and LX compared to other carriers, but I‘m certain it‘d provide information for an amazing sociocultural study if anybody ever wanted to do that...


On the topic of underwear or no underwear: I‘m a no underwear guy, luckily the PJs on LX are rather optimal for that.