I know that one has been patched but try this one:

Have a gun (Infinite ammo would be best), throw the weapon you wanna dupe on the ground and keep shooting it, don't stop. While you're shooting it, have your partner pick it up.
It should give him/her the weapon and it should also still be on the floor for you to pick back up.

I think there's also a money glitch, I saw some guys doing something that looked like it anyway.

I think what you have to do is have a gun (Infinite ammo would be best, again), and keep shooting a cash register with money in it. Your partner should be able to continuously loot the cash register without the cash ever going away (Until you stop shooting).

Hope this helped!

Actually, the original glitch where you throw your weapon and then drop it wile it's in midair still works as long as you delete your Game Patch and redownload afterwards it should still be there for online use.

eggie212 wrote Actually, the original glitch where you throw your weapon and then drop it wile it's in midair still works as long as you delete your Game Patch and redownload afterwards it should still be there for online use.

The way I posted is easier, or I found it easier anyway.

-AdulfTurbopad.