shittings
A cool way of saying that you have diarrhea or wen used as "I have the shittings" suggests that the user has to shit badly or had shit plenty before.

Check the definition yearwood for the type of person that has the regular shittings.
(in a school)
Student 1: Why did u miss class this morning?

Student 2: I had a serious case of the shittings.

Student 1: Damn..

(In a classroom)

Student : Miss, can i go to the bathroom please!

Teacher: But u just went!

Student: But miss, i have the shittings..

Class erupts in laughter.

Teacher: Fine, go ahead..