The sum total of all biochemical reactions that occur in a person's body. Digestion of food is just one aspect of metabolism.
Divided into catabolism, where organic molecules are oxidised and degreaded to prodice energy, and anabolism, where small organic molecules are combined to form larger ones at a cost of energy.
When you go to the toilet to do a wee and you unexpectedly do a poo too.
When Stinkbot when to relieve her bladder before she went running with Fitbot she had a metabolism surprise. Fitbot was glad she didn't need to use the loo after Stinkbot had a metabolism surprise. Poowee stinky!