If it’s a late flight I sometimes change in the lounge throw my jacket on top and walk to the gate in my Jammies. If on a connecting flight at Doha for example, I will sometimes not bother changing out of my Jammies on the first flight and transfer in them . It’s a bit liberating and I then don’t have to worry about my belt at security . Upstairs on the a380 in business the toilets are huge and a pleasure to change in . In others I feel like a contortionist. I remember once a sensible CSD inviting people to change behind a curtain near an exit door .