Expressions used in Everyday Spoken English in Social and Professional contexts
When you 'blindside' someone, you do something they didn't expect which has negative consequences for them. It's not exactly the same as just a negative surprise, because it usually involves preventing them from achieving an expected goal or reaching a destination. You might think of this word in terms of motor racing, where the car behind the leader accelerates on the blindside (where visibility is low) and passes the lead car to win the race. In this scenario, the second car 'blindsided' the leader to achieve victory.