The hèng reading carries two related ideas, both of them 'sideways' in a figurative sense: people who are bullying/unreasonable (going against the grain) and events that drop in sideways (out of the blue). Key fixed expressions:
蛮横 (rude and overbearing),
专横 (imperious),
强横 (tyrannical),
横财 (windfall, usually ill-gotten),
横祸 (unexpected disaster),
飞来横祸 (calamity out of the blue).