The first week I started in the lab in Grad school (back in 85), the lab went to a conference on yeast genetics in Toronto. We had me, my advisor, another grad student, a lab tech (all of us American natural born citizens), and three people with green cards. Going into Canada we all had to get out of the car and the nonUS citizens went into the office at the Peace Bridge for about 19 min to have their papers inspected.
Coming back at US customs. the man in the booth looked at their papers quickly and asked us why we had gone to Canada. We explained and then he asked us how many cases of beer we had in the trunk. We were perplexed at the question He said " Since you study yeast, why didn't you bring back some beer? You could have brought back a case a person duty free!😀"
This part is for the people that either didn't grow up here or move when little: Back in the late 70s we have a car full of guys going to the strip clubsin Ft. Erie. At the Canadian customs, we would just say " Canadian Ballet" abd he would say "Have Fun!"