To throw up after drinking lots of booze. A phrase used to let your buddies know you are gonna go and heave somewhere, but fool the hoes so they don't know you drink like a lady.
This is a more inside way of saying you have to drop a deuce (take a crap), it works really well in an office setting so that you may let your close, personal co-workers know where you are going without letting everyone else know. This is derived from John Wayne's nickname being "The Duke", and can be shortened by simply saying "I have to make a phone call", or added to by saying "man John Wayne has been calling me all day."
This is where when your in a big crowd of people, and instead of saying, "I need to take a shit." You say, "I need to make a phone call." Its a nicer way to put it without being rude, and its just funny as hell to people who dont know what your talking about.
Sammy: "I really need to make a phone call."
Rebecca: "Then go haha"
Joe: "What you guys talking about?"