Sorry, when people say "I can't imagine that," they're usually talking about their own lack of imagination, and not about the unlikelihood of the event that they're describing.
Atvainojiet, kad cilvēki saka, ka nevar kaut ko iztēloties, viņi parasti runā par paša iztēles trūkumu, nevis par attiecīgā notikuma neiespējamību.