What is gastro-colic reflux?

I think you mean : gastro-colic reflex- it is one of the physiological reflexes in the gi tract. Essentially, it is the urge to have a bowel movement after you have had a meal. The stomach stretches and the colon increases motility.

Emptying of colon: Gastric-colic reflex refers to reflex emptying of the colon after a meal. When food enters the stomach this can lead to stretching of the gastric wall. Further , hormones are elaborated by food intake. The result is emptying of the colon after eating. Some people are more sensitive than other to stretch and hormones and have exaggerated responses. Some patients with IBS can have such a response.