Английский словарь американских идиом - trip up

{v.} 1. To make (someone) unsteady on the feet; cause to miss a step, stumble, or fall. * /A root tripped Billy up while he was running in the woods, and he fell and hurt his ankle./ 2. To cause (someone) to make a mistake. * /The teacher asked tricky questions in the test to trip up students who were not alert./