Origin: Singlish/Army Lingo – a corporal punishment in army in the form of 20 push ups
Drop 20 is an army lingo that is used by instructors to give recruits or trainees a corporal punishment of 20 push ups.
This punishment is usually meted out if the soldiers failed to follow instructions or did not perform the task to the expectation of the instructor.
Sergeant Lee: “Recruits!! see that tree over there?? Run over there, touch it, shout I wanna book out and come back to me within 30 secs! Go!
After more than 30 secs, Sergeant Lee: “Recruits! You took more than 30 secs!! What is this?!? Whole lot drop 20!!