In the nip Ireland informal slang
Not wearing any clothes
I was embarrassed as she saw me when I was in the nip.
Completely naked
1. Used to talk about a wide happy smile
2. Used to describe someone naked
It was often said by a photographer when he would like small children to look at the camera and smile before he took a photo.
When the photographer said “watch the birdie”, all of us looked at the camera and smiled.