"Magnemite, the Magnet Pokémon. Magnemite attaches itself to power lines to feed on electricity. If your house has a power outage, check your circuit breakers. You may find a large number of this Pokémon clinging to the breaker box." – Pokédex entry for Magnemite.
"Do you use your Magnemite to charge your phone?" Kumiko asked Shuichi, reasoning that was the only reason he kept his Magnemite. "Seems like something you'd do to save on electricity costs."
"Are you crazy? Of course not!" Shuichi exclaimed, then calmed down upon seeing Kumiko's confused reaction and began to explain his reasoning. "Since Magnemite emit very strong electromagnetic waves, they'll cause any electronic device near them to go haywire! Call me anything you want, but I'm not that stupid!"
"Who knows? Considering that you literally named your Magnemite Magnet, maybe you are." With no polite way to respond to Kumiko's blunt barb about his intelligence, Shuichi simply kept his mouth shut. Anything that he could possibly say would definitely be used against him now.