cake frosting question

does anyone know what kind of cake frosting I can use? I'm looking for whipped topping, I would use Cool Whip but I don't know if it would melt if I left it out and I don't want to put the cake in the frige because then the cake doesn't taste as fresh IMO. I need to bake a cake tommorrow for my dad's B-day.
Since I don't have any money I just decided to cook him a nice dinner and bake him a cake. I am making a vanilla cake with chocolate pudding in the middle but I don't know what kind of frosting to use. I don't like the frosting that comes done already in the container because it's too sweet. Any suggestions?