Monkey bars are obtained from Solihib's Monkey Food stall on Ape Atoll for 50 coins.
Apart from healing 9 hitpoints when eaten, this is item is used in farming as part of the payment for protecting a spirit tree.
They help alot, when a Player has low agility and trains at Ape Atola agility course. Bring some coins when training, and when low on health, buy some monkey bars to heal.
It looks like a chocolate bar.