Back in the 80's I worked for an American airline at Gatwick.
Every 4th of July I got hacked off with the crews wishing me, a brit, a "Happy Independence Day" but in due course found a suitable reply. "Thank you Sir, but remember we got there first."
=============
Being a keen photographer I visited Coltishall just prior to it's closing when an exchange visit took place with visiting Polish Su-7s. A formation of one jag and 3 Su-7s departed using a 6 squadron callsign so I stuck their ops freq into my scanner for a heads up for their return. I almost missed the photos as I was still laughing at the call to ops. "Canopener, Canopener, trousers down in 5 minutes."