to do a Flynn

The phrase 'the art of a Flynn' was a saying in movies referring to going to the toilet and excreting one's insides.

A 'colossal Flynn' would also be referenced, meaning to perform the act twice in a row.

person 1 :i need to go and do a flyn

person 2: lets hope its not a colossal Flynn

person 1: i fear to do a Flynn