After giving the Saints a first-half lead, the attacking midfielder raced to the corner flag and mimed, er, wiping his backside.
On first glance, it appeared pretty disrespectful, but happily Puncheon was just having a joke at his own expense.
Last month he had to sprint from the field to answer the call of nature during a goalless draw against Everton.
The incident caused the newly-appointed Southampton boss Mauricio Pochettino to quip: "When there is a new manager, the players want to impress and sometimes nerves get the better of them."
Puncheon has since been on the end of much light-hearted banter, so decided to re-live the fateful moment after scoring.
The Southampton fans certainly loved it, breaking into a chant of "He s***s when he wants."
And there were more celebrations on the south coast as Southampton went on to thrash City and go 15th in the Premier League table.