>>14079290True story.
Three chinese students occupied two standard class room tables, which they pulled together.
Technique: they passed notes with answers between them from left to right or vice versa.
I was the professor who gave the exam, and I also oversaw it.
A clumsy one of the three lost one such note which dropped to the floor.
I calmly went to pick up the note and gave it to the closest one of the three students.
"Is that yours?" Some nodding ensued. I returned it back to him, and let them finish the exam.
Guess how many of them passed. Lol.