poking daylight 

When you have to shit so bad that a piece of shit is almost or seems to be poking out of your ass.

I had to go so bad I was poking daylight.

poking daylight by Pestac September 20, 2004

pokin daylight 

to have the crown of a shit poke out of the anus.

"I thought it was just a fart, but I ended up pokin daylight.

pokin daylight by colonel Hogan May 13, 2003