To be quite honest I doubt giving chocolates to ANY agent will make a difference.
The receiving agent could be in a lot of trouble if it was discovered that the agent did something they should not have done because they got a box of chocolate!
How would you feel if you saw a non-rev give a chocolate bribe and got on a flight/upgrade before you when you know you had a higher priority??
To be honest i think it is a rediculous idea!!