Line a baking sheet with wax paper. Peel the bananas and then slice in half lengthwise. Carefully insert a stick into the bottom of each banana and then place it on the baking sheet. Freeze the bananas for 1 hour.
Melt the chocolate chips with the vegetable oil in a deep metal bowl set over saucepan of barely simmering water stirring occasionally until the mixture is smooth. Remove the bowl of chocolate and set aside.
Remove the bananas from the freezer and 1 at a time dip them in the chocolate smoothing it over the entirely of the banana with a spoon.
Repeat the dipping and decorating process with the remaining bananas and then return them to the freezer for 10 minutes or until the chocolate is firm.