Three things you could do here.
1) You get half the pay, you give half the effort. I don't see any other monkeys hanging around looking at replacing me in my rock dropping job. So when she want's me to give her the rock, i will be just pushing the rock out to her side. Half the effort for half the reward.
2) Fake a monkey heart attack. Oldest trick in the book. When you cage is open make a bee line for the grapes.
3) Make an agreement with monkey number two, i give him my rock and in return i get half the grape when he hands it to the person. She will be so shocked that i have created rudimentary economics that i may expect a grandios prize or perhaps a vivisection.
4) If monkey doesn't give me rock:
a) Keep on giving rock, eventually monkey number two will get full and will give me excess food. I will store this food like and live like a king for a day while the person gets their own damn rocks.
b) Act the fool and continue to give the rock over to second monkey. As he gets fuller the slower he will become. I feign fatigue with passing my rock over for the 7th time, i think i see some remorse in the persons face at the scene of futility before them. I however would not know, the persons eyes are only made out and they are as cold as my cage. The second monkey is getting restless as i am not giving over the treat bringer as quickly as he would like so he can gorge himself on the sweet sweet grape. He rudely shoves his hand into my cage to hurry the process of his gratification. Like a monkey ninja i drop the rock and grab just above his wrist. I pull hard, bearing all my weight against the cage wall, forcing his round stupid face into the iron bars of fortitude. Before he can compose himself my left arm has gone through another cage opening and wrapped itself around his throat like a python. There is definitely shock in the persons eye's now. I release my right hand and pass it through to the persons realm and point to the grapes. Her mouth is viewed for the first time as it matches her wide eye's. She slowly reaches for a piece of cucumber and my vice like grip around monkey number stupid tightens, releasing a squeak from his trembling frame. Her hand instantly dances to the grapes as king monkey and person communicate in near telepathic sense. She hands me a grape and i casually drop it in my cage. I then reach out once more and motion for her to make it rain grapes while nodding slowly. Clever person.
5) use rock as projectile to knock out person. hopefully damaging cage enough for escape.
6) masterbate while looking person in the eyes.
7) poo attacks.
