A secretive handing over (usually of money) in exchange for certain favouritism (usually by some sort of authority)
The Businessman gave a back hander to the Politician in order win the large contract.
OR (NZ example)
Peter Sumonivich gave a back hander to Winston Peters in order to obtain a more favourable fishing quota next season.
The Pharmaceutical comapanies gave back handers to numerous doctors in exchange for them promoting certain medications.
1 - A person who has sex with or masturbates to muppets
2 - See Arsehole, cuntbag, dickhead, dickshit, motherfucker, cunt, homo, idiot, jerk, pig, fucktard, arseclown etc..
John Key is a muppet Fucker