Mom's Wacky Chocolate Cake

1 1/2 c. SR flour
1 c. sugar
3 T. cocoa
1 t. vinegar
1 t. vanilla
5 T. oil
1 c. water
Topping:
2 c. sugar
2 T. cocoa
1 stick margarine
1/2 c. milk
1 t. vanilla

Spray 8" square pan. Combine flour, sugar, & cocoa. Spread in pan. Make 3 holes in cake. Put vinegar in one, vanilla in another, and oil in the last. Pour water over the whole thing. Mix well with fork. Bake at 350 degrees for 25-30 minutes. Bring topping ingredients to a boil for 1 minute. Cool, beat, and spread over cake.