an expression that is intended to convey excessive excitement. the beauty of the expression is that it has a double meaning; one literal and another entirely figurative but much more ridiculous.
1) to be shitting in one's pants 2) to be excreting pants from one's rectum
(over the phone): hey broski, guess where i'm at? in line to see the offspring. i'm shitting pants!
Employee 1: "Man its been a long day at work."
Employee 2: "You know what I do after a long day of work? Go home, shut the door, close the blinds and do some Swifting."