In the BGT show, a boy, Ned Woodman does a joke as performance. During his performance, he said
Why are people so excited talking dog on Britain's Got Talent. Amanda Holden has been on it for years.
And they show audiences' happy face of laughing. But I don't know why it's so funny.
What's the meaning of 'has been on it' here?
This is the youtube link of the performance: https://www.youtube.com/watch?v=0qxIyOFkJeY
I listened to the joke in the wrong way and I fixed the content with the help of the comment below. ('spin on it' -> 'has been on it')