Instant messaging is a weird way to communicate because, unlike talking on the phone or in person, you don't know if the other person is saying something until it's right there in black-and-white. Sometimes both people will type at the same time causing an overlap in the conversation. This can lead to some awkward exchanges.
Take this one from a recent chat with my sister:
Sandy: [Our close friend] died yesterday in a horrible accident.
Me: I saw a goat today.
Sandy: He fell asleep at the wheel.
Me: Just running down the street.