For Dalton, it's 'you're funny!'
He seriously says it to adults when they say something to him and he's not quite sure how to respond. It normally gets a laugh in response, so perhaps HE is the funny one....
Sat Mar 01 2014 18:59 the 'Go-to':
Everyone has a go-to phrase, something they say when they don't know what to say. For Mary Poppins, it was supercalifragilisticexpialidocious, for example.