Gaandu is derived from the Hindi word Gaand. Traditionally Gaand means the Ass. Gaand is a noun and Gaandu is an adjective.
Mainly Gaandu is referred to a gentleman who licks someone else's Ass or Gaand in order to get benefits. It can also be referred to someone who gives his Ass for the same thing.
aray gaandu............
oi bender (has no equivalent in english as all english terms relate to a trait e.g. arse-bandit, shit popper) whilst this is just everything in one