The talent show judge told Metro that she welcomes the stranger examples of Britishness on the show.
"Think outside the box," Holden urged contestants seeking her vote.
"I don't want anything too contrived but we're renowned for our eccentricities."
She added: "We've been celebrating our Britishness with events such as the Olympics and the Diamond Jubilee, and long may that continue.
"I'm sure there are lots of naked unicyclists who eat fire while juggling dogs and I hope to see them at the auditions."
Of whether the newer judges should respect her authority as the longest-standing member of the panel, Holden said: "No. We all do our own thing and value each other's opinion, no matter how long we've been there.
"I gave David [Walliams] and Alesha [Dixon] the same advice Simon [Cowell] gave me - just say what you think."
Holden recently claimed that Cowell's other talent show The X Factor is "boring", adding that she never usually watches it through to the end.