The "Bribe" ability is an extremely useful ability in its own respect. By quite literally paying your enemies, Rikku can nab some of the best items in the game. Be wary! This move is extremely expensive. Use it if / when you really need to only.
The first thing you need to do to use Bribe is to, of course, learn it! It is an ability on the sphere grid that will most likely be learned by Rikku first. After using bribe and finishing a battle, your will gain your item(s). The following is a list of items you can get by bribing: