It's rude to hang up on a friend.
David is talking to his friend Adam on the phone and it is getting close to bed time.
David needs to get off the phone to get ready for bed.
David waits for a break in the conversation and tells Adam he needs to go.
David hangs up on Adam while Adam is in the middle of talking.
Adam and David amicably end the conversation.
Adam is offended by the sudden end to the phone call.