Ant and Dec are expecting Simon Cowell to ''crack'' and fire David Walliams from 'Britain's Got Talent'.The duo - who host the TV talent show - have joked the comedian could face the sack for his continual jibes at his fellow judge. Declan Donnelly told The Sun newspaper's TV Magazine: ''David is constantly on the naughty step but he climbs off it and keeps on teasing - and there is no sign of that letting up. ''Simon is starting to crack. David could be fired by the end of this, let's be honest.'' His co-star Anthony McPartlin agreed he would be shocked if the former 'Little Britain' funnyman survived the series. He added: ''Yeah, I'll be surprised if he makes it the whole way through the series.'' The pair, both 37, also took aim at boss Simon, 53, for being like ''a nine-year-old boy'' with his interests and dreams. Ant said: ''Just think of what a nine-year-old boy would like and that's what Simon likes.'' Dec worries what the music mogul's new dream act could be after finding Pudsey the dancing dog last year, but revealed the music mogul loves ''robots and cartoons''. Asked if he thought the duo featured in his dreams, he admitted: ''Oh my God, I hope not. There is a bit of a worry that now he's found his dancing dog, what else does he want? ''We know he's a big fan of robots and cartoons.''