The 3:51 cart% run uses an inventory duping glitch instead of rubbing items against the pawn shop shredder. How does that glitch work? I've looked for tutorials for it but I can't find any.

Edit: After playing around with it, it seems to be something with dropping an item with left click, and mashing Tab and F to cause it you to pick up the item twice before the inventory menu can finish coming up. I don't know exactly when is the right time to press the keys, but mashing it and quickly hearing the item pick up sound twice means the dupe worked.

Edit 2: The order to press the buttons is Left Click, Tab+F, F in quick succession. Left click will drop the item from your inventory, Tab will start closing the menu and F will pick up the dropped item, pressing F again quickly will pick it up again while it is moving towards you.

I posted it in guides, but I didn't explain it to in-depth admittedly. You can buffer the "pick up" key, I changed it to my side mouse button in settings. Hold the pickup key the entire time, look at a 45 degree angle down, and then left click once (spamming it will cause the item to be grabbed out of the air), and then spam tab right. Do this 9 times. Its kind of tricky because you have to press tab right after left click, but not before.

this a vid i posted back in feb 2019 (damn thats 2 years ago) the timestamp is for duping