1.) Loot up so that your inventory is 100% full and place the weapon or item that can be placed in hand into item bar.
2.) Pull item out (example, pistol)
3.) Find another item to place in your inventory to block the 4 slots of the pistol.
4.) Pick up a can to drink, or hit the hotkey on the item bar to "place it back" in your inventory. The item may end up on the ground without the users knowledge. In houses, items may disappear or be placed at one of the doorsteps.