"Why are you visiting Canada?"
-I'm not visiting Canada. I'm just connecting from Frankfurt to San Francisco.
"Where did you originate today?"
-Budapest
[extended questioning about overnight stay in Budapest]
"How long will you be in Canada?"
-Hopefully about two hours
"So why do you want to enter Canada?"
-I don't want to enter Canada, I'm just here to catch a connecting flight and there's no airside transfer."
[sends me to Secondary]