These are super easy, and your gerbil will love them!!
Here is a list of the best things to put on their kabobs...
Red Pepper (or green/yellow pepper. Red has the highest vitamin C concentration)
Carrots - both the root and the green tops are perfectly safe for your guinea pig.
Apples - just make sure they don't have any seeds.
Leafy greens like red lettuce, romaine, Boston lettuce, (be sure to feed leafy vegetables in moderation to avoid diarrhea, and feed spinach a bit sparingly to avoid potential kidney problems.)
Broccoli (in moderation since it can be gassy and cause a gas pain)
strawberries (in moderation)
oranges or clementines. A helpful way to feed these to your piggie if they're being picky is to scoop out some pulp from half an orange and leave some in it so they can lick it without needing to chew on it if they're not diggin' the texture.