1) Totally unfounded, not
credible, or ridiculous...usually refers to something somebody just said.
2) Having a large amount of
fecal matter in your body, usually necessitating
a dump.
Eric: "...so I told
the Olsen twins I wasn't in the mood, because you know, I can
do better. Then a couple minutes later I ran into
the Hilton sisters and scored a threesome. It was just like in the video, dude, I swear."
Stan: "Man you're so full of shit, your eyes are brown."
Eric: "Yeah, I guess you're right, I really need to drop a massive deuce in the john."