Slow shrink with the family

The next day

Zack awoke to a beautiful sunny day. He stretched in bed and sat up. It took a while for him to get himself together as he sat and tried to wake up. The clock read 11:15am. Time to get out of bed for breakfast. He jumped out of bed but felt a bit more of a drop. He shrugged it off but even the stairs seemed higher up and he nearly tumbled down them midway. Eventually, he got to the kitchen where he poured a bowl of cheerios. Rebecca, the 2nd oldest sister who was 19, came strolling in, her long red hair covering her well hungover face as she shuffled to the bowls. She made her cereal and sat down at the table across from him. The milk almost poured out the bowl as she slammed it on the table and dived into her cheerios.
"So you gonna gimme a lift today? I need to be at the mall by 12," she mumbled with a mouth full of food.
"So gross, swallow that before talking to me and yeah I remember, guess we better get ready to make a move soon then."
She hastily shoved in the last of her cereal and with a gob full just opened wide in front of her brothers face.
"You really are just gross, far from lady like," he said in a fed up tone as he jumped off the seat.
She swallowed the last of it and headed to get ready. as she stood beside him his size difference had become apparent.
"What the..? You know you're now shorter then me, right?"
Although he didn't like to admit it, she was right, he had gotten a couple inches shorter over night.