grow a tail

To grow a tail is a metaphor, as the anus where poop exits is adjacent to where a tail is placed. "Growing" in this case refers to partial expulsion as one attempts to prevent it.

grow a tail (third-person singular simple present grows a tail, present participle growing a tail, simple past grew a tail, past participle grown a tail)

1. (vulgar, idiomatic) to be nearly about to defecate, to the point of being unable to completely hold it in
   • 2000 Larry Glanz The Ultimate Book of Bathroom Etiquette and Humor pg 146 and pg 152

     When man needs to grow a tail, man must run to bathroom without fail.
     Thou shalt groweth thy tail with great care, or though might staineth thine underwear!

   • 2009, Ann McDeed, No Greater Love, page 206:

     Kathy is teasing Dad that Mom is growing a tail in the toilet. Guess he understands to a degree and had a strange look on his face when I came out, so assure him I am fine and did not grow a tail.

   • 2012, Tyson Jopson, Best of Getaway Funny Signs, page 28:

     A steaming pile of toilet humour might not be everyone's cup of tea, but there's no denying the hilarity in some of these messages from beyond the bowl. Our readers managed to snap these delightful deuces before breaking the seal, splashing the pirate, building a log cabin, growing a tail... you get the idea.

   • 2016, Vanessa Hawkins, Gloryhill, page 91:

     The only other guy doing any work around here was the fat old cop down in the can, strugglin' to grow a tail.

• crown
• breaking the seal
• splashing the pirate