the only way i know: if server got problems and you get dc+ rollback some minutes you can trade an item to someone who dont get dc+rollback, this person leaves and the item transfer will be changed for this person. If you get ur dc+ rollback you might still have this item in your iventory. Yes this is a trade glitch, but you cant usually use it because there are usually NO rollbacks. anyways due to maintenance, patches and server instability r this.ks may happen. this is when you might to try this.