Happy Birthday 2 U & U & U

In an all-computer controlled future, a senior and tween have birthdays in different homes. The tween demands a birthday cake and her mom isn't sure what it is, so she gets the computer for help and after a cake is baked, she and her daughter do nothing with it. Granny wonders if it sings and celebrates her birthday lonely; an alien invades and hears this so it takes the tween's cake to her for celebration.