A "Sophie Moment" is a moment of extreme stupidity or daftness experienced by someone. The phrase developed after the beautiful Princess Sophie kept on making silly remarks and comments. When someone does or says something of equal muppetness they are said to have had a Sophie Moment.
Sophie: Oh my God! There's a huge bug on my arm! Get it off! Get it off!
Rob: What?! I can't see it! Where is it?
Sophie: Look where my eyes are looking!
Rob: How am I supposed to do that?!
Steve: Now THAT, was a Sophie Moment!