Lady Gaga once autographed a fan’s penis.

“I feel embarrassed saying this but the strangest thing I ever autographed was a man’s penis,” she laughs.

The 23-year-old “Just Dance” star was left red-faced singer when a smitten admirer made the X-rated request following a performance in Canada.

“I was doing a meet and greet backstage in Canada. I had enough room to write Lady GaGa but I don’t really remember. I was laughing so hard I could barely breathe. Maybe it is still there – who knows? It was a permanent marker too!”