Do you know what duds are?

Although all of these ventures failed miserably, the McLean Deluxe takes the cake, er, bun. Composed of beef and seaweed, the low-fat sandwich tasted about as bad as it sounds.

Only an idiot would think of some thing like that to say, shun you.

like anybody knows.

The I know song

I'll take a stab at it: This seems to mean that it is a high order of knowledge to have a sense of the limits of one's knowledge. Being 'smart' and 'informed' or 'savvy' is great, but being aware of...