I must confess over the years I have spawned the gamut from wargaming DM to stream of consciousness DM, hard core rules stickler to whatever is fun. Time to time I've caught myself using a real world prop to show folks no you can't do that.
The sword slung over the back: a player argued it's work for his longsword I told him he was wrong (and I should have let it drop there and let him play with a goofy looking character) the argument raged detracting from game play until I went and got my practice sword of the time (a wooden katana of some sort), we rigged the scabbard carefully as we could and low and behold the players arms just weren't long enough to draw the sword with it slung over his shoulder.
We can fight in this space: A player argued two characters could most certainly fit in a 5' space and fight with one using a polearm and the other a sword. The argument was stealing game time but I went and got this big long staff my dad had at the time (probably only 6' long) and a new boffer sword I had created, the player and stood in the hall next to my parents bathroom, it's about 5' by 6' and we pretended we were fighting someone in front of us. After getting boffed a number of times the arguing player relented.
It' shouldn't take me that long to search a door: a player didn't think it would take more then a minute to search a door properly (I think I was using 2-5, 1 minute rounds back then) that any fool could do it in ten or 20 seconds. We argued, I c am eup with a plan I old the player I was going to rig a trap the same one I used as an alarm to let me know when my little brother or parent had been in my room when I wasn't there. After rigging the "trap" the player was let lose to find it. After about thirty seconds he found the penny wedged in the door jam and announced it was there I said "fine open the door" so the player did and the other penny secreted along the top edge of the door fell to the floor "oh look, ANY fool can't find a trap in 10 or 20 seconds".
Sneaking in armor: Turns out you can sneak in all sorts of armor. I learned this from experience playing LARPS I had this ridiculously heavy and noisy set of scalemail, thin metal scales on a leather backing, I looked like a disco ball in the sun light and it sounded like someone throwing silverware down a staircase when I ran. Not wanting to have 4 to 40 fellow larpers in elf ears and over sized padded weapons to beat me savagely while night questing I simply learned how to move and make no noise in that very noisy suit of armor, the trick was slow and calculated moves that probably slowed my travel speed down to about 1/10th normal but I most certainly could sneak in cumbersome poorly designed clanking armor. I'm certainly not a high level thief in real life either.
Reality checking can be silly, waste a lot of time but now and again a little actual physical experience really sets the record straight.