Translation:They fill their bags with bananas and peanuts.
World literally means bean but is also used for some of nuts. For example peas (kacang hijau = 'green beans'), kidney bean (kacang merah = 'red bean'), cashew (kacang mete). If 'kacang' is without any aditional word, usually points on peanut. Peanut full name is kacang tanah.
Epic prank, bro! Now they'll wonder if they accidentally took the bag of a monkey and left their bag for the monkey to take! Classic!