i am most impressed by su-lin's mother, who can cross-examine five-year-olds in her kindergarten class as cunningly as any courtroom lawyer:

eroi: mrs lye, i want a sweet
children, severally: he took one already! mrs lye, he already ate his sweet!
mrs lye: eroi, have you taken a sweet?
eroi: dunno
mrs lye: eroi, did you eat your sweet?
eroi: dunno
mrs lye: what colour sweet did you have?
eroi: yellow

you can see the rest of the entry from which i excerpted this conversation on su-lin's blog.