You shouldn't use your friend's phone without their permission.
Lisa's phone is out of battery, and she really needs to make a phone call, Bart's phone is right there.
Lisa wants to call someone right now.
Lisa plugs her phone into the charger and calls while the phone is plugged in.
Lisa takes Bart's phone without premission and calls with it.
Lisa finishes the call and she sighs in relief afterwards.
Bart finds out when they call back - on HIS phone - later on.