rat trying to get out 

When you gotta shit so bad that the shit pops in and of your arsehole as if convulsing. See Prarie Dog or Seismic Fart.

To wanna shit really bad, but have to hold on while farting your guts out rotten!

To be prarie dogging while farting.

To paint your undies with a brown skidmark and flavour the room with he scent of shit.

I was sitting on the train when this guy moaned, "rat trying to get out!"

"Next thing I knew I was on the floor choking to death, passengers were jumping to their deaths from the moving train and one woman even stabbed herself to death with her knitting needles to save herself from the filth in the air!"

"While coming out of a coma in hospital the nurse said the papers called it, The Seismic Fart of the Century!"

rat trying to get out by The Moody Poet February 3, 2007