Years ago, I read a memoir called The Lucky Bastard Club: A B17 Pilot in Training and in Combat, 1943-45 by Eugene Fletcher. Among the stories he related included tales about his first trainer, a Stearman biplane. For the student pilot to communicate with the instructor pilot, they had a device called a gosport, which was basically a hose with a funnel on each end. One man would hold the funnel on his end up to his face and yell into it while the other held his end up to his ear.
When they moved up to the next trainer (I forget if it was multi-engine or just had an enclosed cockpit), they had electronic headphones and mics for communications, but they still had what appeared to be a gosport. Fletcher couldn't figure out why they had a gosport in a plane with electronic communications equipment, but he didn't think much about it until one day when he and one of his buddies got done with their flying for the day. They both landed around the same time, so Fletcher waited for him, but he didn't show and didn't show and didn't show. Finally, the guy showed up, very green around the gills, and told him what'd happened. He'd tried to use the gosport, which involved holding the funnel up against his face, only to learn that it wasn't a gosport.
It was a relief tube.
Yeah, he'd just spent the last half hour puking his guts out over that mistake.