The phrase "moving the goalposts" originates in England and almost certainly comes from football there (soccer), and if not soccer, rugby. The "poles" of the goal in question are called goalposts, as I can assure you having grown up in South Africa and knowing about my shots "hitting the post" long before I knew of American football. But sure, *I'm* the one who needs to get out more
Fun fact, if you want to search for an actual instance of someone moving an actual goalpost, you will find a Swedish goalkeeper moving a soccer goalpost.
Ask 100 people which is the goal and which are the goalposts. Then come back and apologize. 
It's sad that this is not even in the top 10 stupidest arguments we've had, but this is moronic. It also uses a classic one of your techniques: pigeonholing someone into an uber specific opinion or definition to force them to negate any kind of nuance or context.
One is a goal, one isn't, so if you had to choose one, obviously, you choose the football posts. But the soccer goal has two goalposts, and ask those same 100 people what the gif I posted means and they'll say "moving the goalposts."
Also, using the phrase "you need to get out more" to correct someone when the issue is your own limited knowledge due to ignorance of a foreign phrase is, shall we say, a bit of an own goal.
