Subedar Dhruv Singh Thapa of 1/9 Gorkha Rifles (First Battalion The Ninth Gorkha Rifles) was posted as a drill instructor at The National Defence Academy (NDA) when I was a cadet (an officer trainee) there back in 1989-90. He was the senior drill instructor of my squadron and was a hard taskmaster. He wouldn't accept the slightest slackness while putting us through our paces on the drill square in turn-out, marching, saluting, arms drill and so on.
I completed my training at The NDA and at The IMA and was a newly commissioned Second Lieutenant (We had that rank in The Indian Army back then). I had opted for The Gorkha Rifles and as luck would have it I was commissioned into 1/9 Gorkha Rifles. Dhruv Singh Thapa had by then been posted back from The NDA to the unit (1/9 Gorkha Rifles) and had been promoted to the rank of Subedar Major - the senior-most JCO rank in the unit, but nevertheless a rank junior to Second Lieutenant (Which is a commissioned officer rank).
I duly joined 1/9 Gorkha Rifles after my post commissioning leave - a rookee 2nd Lt joining his first unit and was received by Dhruv Singh Thapa at the railway station.
The next day - my first day on duty as a commissioned officer in The Indian Army - I was outside The Commanding Officer’s office waiting to be called in by The CO for an interview when Subedar Major Dhruv Singh Thapa emerged from The CO’s office and on spotting me saluted smartly (I was his senior officer now).
Newly commissioned as I was, I wasn't yet used to being saluted and perhaps the salute I returned was an awkward one, for, he stopped and walked up to me, Subedar Major’s cane smartly under his left arm, looked me in the eyes and said “Sahib, this isn't the kind of salute I trained you in at The NDA”. He then added, “ I shall salute you again and would request you to salute me the way I trained you”. . . and that's what he did. Went back a few steps, passed me again and saluted me again.
Needless to say, I have never ever been sloppy in returning a salute since!